1. MAGIC AND PSIONICS
A: That's a big question, berk. There are lots of things a blood wizard has to remember when he's casting spells, the first being where he's standing. Many magic spells draw their energy from other planes, and if the wizard's cut off from these places, his spells function less effectively, or not at all. 'Course, this works the other way round too: Some planes enhance spells which are related to them. Still more complicated are the alterations to certain schools of magic. See, the planes have their own themes and personalities, and they don't take too kindly to spellcasters going against their essences. Some spells are entirely negated (like Illusions on clockwork Mechanus or Divinations on the mysterious Ethereal) and in other situations they're diminished (like Enchantments on mean-spirited Gehenna) or enhanced (like Fire spells on the Elemental Plane of Fire). Some schools of magic are altered: The Planes of Chaos tend to pervert Alterations, while harmful Necromantic magics might be revisited on the caster or negated entirely, depending upon the Upper Plane. Many of these alterations or restrictions can be avoided with the proper use of Spell Keys (q.v.), but some absolute restrictions cannot be avoided. Amongst these are the Spire's negation of magic, and the ban of Wild Magic on Mechanus. Priest spells are generally unaffected by the plane they're cast on, as the Will of Powers is enough to overcome most local conditions. For example, a priest can cast the astral spell on the Inner planes, even thought there's no natural Astral connection: His power's might is enough to allow this spell to work. However, the absolute prohibitions still remain &emdash;no matter how mighty your Power, you still can't cast spells at the Spire! The many intricacies are far too numerous to mention here. Details can be found in The Planewalker's Handbook, p 102-107.
A: That's a big question, berk. There are lots of things a blood wizard has to remember when he's casting spells, the first being where he's standing. Many magic spells draw their energy from other planes, and if the wizard's cut off from these places, his spells function less effectively, or not at all. 'Course, this works the other way round too: Some planes enhance spells which are related to them.
Still more complicated are the alterations to certain schools of magic. See, the planes have their own themes and personalities, and they don't take too kindly to spellcasters going against their essences. Some spells are entirely negated (like Illusions on clockwork Mechanus or Divinations on the mysterious Ethereal) and in other situations they're diminished (like Enchantments on mean-spirited Gehenna) or enhanced (like Fire spells on the Elemental Plane of Fire). Some schools of magic are altered: The Planes of Chaos tend to pervert Alterations, while harmful Necromantic magics might be revisited on the caster or negated entirely, depending upon the Upper Plane.
Many of these alterations or restrictions can be avoided with the proper use of Spell Keys (q.v.), but some absolute restrictions cannot be avoided. Amongst these are the Spire's negation of magic, and the ban of Wild Magic on Mechanus.
Priest spells are generally unaffected by the plane they're cast on, as the Will of Powers is enough to overcome most local conditions. For example, a priest can cast the astral spell on the Inner planes, even thought there's no natural Astral connection: His power's might is enough to allow this spell to work. However, the absolute prohibitions still remain &emdash;no matter how mighty your Power, you still can't cast spells at the Spire!
The many intricacies are far too numerous to mention here. Details can be found in The Planewalker's Handbook, p 102-107.
A: Spell keys are little tricks that canny wizards pick up to allow them to bend the rules that the planes have set on magic. On many planes, it ain't possible to cast spells from certain schools, or else the effects of those schools are altered or diminished. Spell keys can be general (which means they affect a whole school on a given plane) or specific (which means they affect only one spell on a given plane). The exact nature of spell keys depends on the plane and spell in question; it's usually a symbolic gesture to the Laws of Magic. Whatever it is, using a spell key'll add 1 to the casting time of a wizard spell. It'd also be best to bear in mind that not every spell has a key: for example, wild magic'll never work on Mechanus, whatever the key, as its nature is just too antithecal to the plane. See A DM Guide to the Planes, p 13 and The Planewalker's Handbook, p. 106. Power keys are rather different. They're much rarer, as they're granted directly from a power to his or her servants, the priests. They can change at the power's whim, and don't usually last longer than a week or so. They're also much more potent: Power keys cause the spell they affect to have maximum possible effect. Basically if there's a random factor in the spell (damage, range etc.) then it always is as large as possible. See A DM Guide to the Planes, p 14, The Planewalker's Handbook, p 109-110, and On Hallowed Ground, p 16.
A: Spell keys are little tricks that canny wizards pick up to allow them to bend the rules that the planes have set on magic. On many planes, it ain't possible to cast spells from certain schools, or else the effects of those schools are altered or diminished. Spell keys can be general (which means they affect a whole school on a given plane) or specific (which means they affect only one spell on a given plane). The exact nature of spell keys depends on the plane and spell in question; it's usually a symbolic gesture to the Laws of Magic. Whatever it is, using a spell key'll add 1 to the casting time of a wizard spell. It'd also be best to bear in mind that not every spell has a key: for example, wild magic'll never work on Mechanus, whatever the key, as its nature is just too antithecal to the plane.
See A DM Guide to the Planes, p 13 and The Planewalker's Handbook, p. 106.
Power keys are rather different. They're much rarer, as they're granted directly from a power to his or her servants, the priests. They can change at the power's whim, and don't usually last longer than a week or so. They're also much more potent: Power keys cause the spell they affect to have maximum possible effect. Basically if there's a random factor in the spell (damage, range etc.) then it always is as large as possible.
See A DM Guide to the Planes, p 14, The Planewalker's Handbook, p 109-110, and On Hallowed Ground, p 16.
Q: How are magical weapons affected by the planes?
A: Magical weapons and armour, and items with pluses are magically bound to their home plane, much like creatures. Unlike creatures, however, the further the enchanted item is taken from its home plane, the weaker its enchantment becomes. Luckily, this isn't a permanent reduction, but it can be a shock for Clueless cutters when they realise they're stranded on a hostile plane and their magic sword suddenly stops being so magic. For each plane of separation from its home plane, the item loses one magical 'plus'. The numbers are best explained by example: A sword from the Prime would lose one plus when taken to the Astral or Ethereal Planes, and two when on the Inner or Outer Planes. The absolute number of planes between the item's home plane and current location are counted, even if the item physically travelled through fewer planes: For example, from the Prime to Sigil through a portal counts as a -2 loss, as the portal technically moved the traveller through the Astral, even if he didn't notice it. Inner Plane-forged items are worse off. On an adjacent Inner Plane (e.g. Air and Ice or Water and Salt) the item loses one plus, as it does on the Ethereal. On any other Inner Plane or the Prime the item loses two pluses, as the item can be traced through the Ethereal back to its home plane). In the Astral, the item's at -3, and on any Outer Plane at -4. Outer Plane-forged items are -1 on an adjacent Outer Plane or the Astral, -2 on the Prime or a non-adjacent Outer plane (the route can be traced through the outlands or the Astral), -3 on the Ethereal and -4 on the Inner Planes. The most useful weapons, then are those forged on the Outlands or Sigil (which are adjacent to every Outer Plane) the Astral, or Ethereal. DMs using these rules should be careful to note the plane of origin of any magic items they allow their players to acquire, especially those with pluses. It's a bit of extra book-keeping perhaps, but introduces a whole new dimension of possibilities to the game. These guidelines are summed up more fully in The Planewalker's Handbook, page 110, and in the massive (epilepsy-inducing) table on page 157. There's also a section explaining this on page 15 of A DM Guide to the Planes.
A: Magical weapons and armour, and items with pluses are magically bound to their home plane, much like creatures. Unlike creatures, however, the further the enchanted item is taken from its home plane, the weaker its enchantment becomes. Luckily, this isn't a permanent reduction, but it can be a shock for Clueless cutters when they realise they're stranded on a hostile plane and their magic sword suddenly stops being so magic.
For each plane of separation from its home plane, the item loses one magical 'plus'. The numbers are best explained by example:
A sword from the Prime would lose one plus when taken to the Astral or Ethereal Planes, and two when on the Inner or Outer Planes. The absolute number of planes between the item's home plane and current location are counted, even if the item physically travelled through fewer planes: For example, from the Prime to Sigil through a portal counts as a -2 loss, as the portal technically moved the traveller through the Astral, even if he didn't notice it.
Inner Plane-forged items are worse off. On an adjacent Inner Plane (e.g. Air and Ice or Water and Salt) the item loses one plus, as it does on the Ethereal. On any other Inner Plane or the Prime the item loses two pluses, as the item can be traced through the Ethereal back to its home plane). In the Astral, the item's at -3, and on any Outer Plane at -4.
Outer Plane-forged items are -1 on an adjacent Outer Plane or the Astral, -2 on the Prime or a non-adjacent Outer plane (the route can be traced through the outlands or the Astral), -3 on the Ethereal and -4 on the Inner Planes.
The most useful weapons, then are those forged on the Outlands or Sigil (which are adjacent to every Outer Plane) the Astral, or Ethereal. DMs using these rules should be careful to note the plane of origin of any magic items they allow their players to acquire, especially those with pluses. It's a bit of extra book-keeping perhaps, but introduces a whole new dimension of possibilities to the game.
These guidelines are summed up more fully in The Planewalker's Handbook, page 110, and in the massive (epilepsy-inducing) table on page 157. There's also a section explaining this on page 15 of A DM Guide to the Planes.
Q: How are psionics affected by the planes?
A: A thorny question, with no official answer. Generally, psionics are considered to draw upon internal energy rather than anything external, so they're affected less by planes than magic. On the Outlands, from the sixth ring and in, non-godlike psionic abilities are annulled (source: A Player's Primer to the Outlands, p 6). Other than this one restriction, the official rules remain very quiet about psionics and their users. This is partly due to the fact that they're an optional part of the AD&D rules, and partly due to the Planescape designers being self-confessed psionophobes. There's an unofficial Planescape Psionics Handbook being put together right now, and as soon as it's on the Internet, this FAQ will be updated with a link leading to it. It will address not only the way psionics works on the planes, but introduce now planar psionic powers, attack and defence modes, and offer an extensive revision of the psionics rules themselves. When it's complete, it will be mentioned on the Planescape Mailing List. Until then, cutters, you're on your own.
A: A thorny question, with no official answer. Generally, psionics are considered to draw upon internal energy rather than anything external, so they're affected less by planes than magic.
On the Outlands, from the sixth ring and in, non-godlike psionic abilities are annulled (source: A Player's Primer to the Outlands, p 6).
Other than this one restriction, the official rules remain very quiet about psionics and their users. This is partly due to the fact that they're an optional part of the AD&D rules, and partly due to the Planescape designers being self-confessed psionophobes.
There's an unofficial Planescape Psionics Handbook being put together right now, and as soon as it's on the Internet, this FAQ will be updated with a link leading to it. It will address not only the way psionics works on the planes, but introduce now planar psionic powers, attack and defence modes, and offer an extensive revision of the psionics rules themselves. When it's complete, it will be mentioned on the Planescape Mailing List. Until then, cutters, you're on your own.
Q: Are there any other discrepancies I should be aware of?
A: Yeah. Careful reading of spell descriptions in the Player's Handbook will reveal a number of spells which don't work when cast on extra-planar creatures. That was written originally to prevent players using certain spells against aasimon, baatezu, elementals, and the like. With the Planescape rules, players can now have characters who don't hail from the Prime Material Plane. For example, the 1st-level Priest spell cure light wounds (as well as all the other priest spells which heal damage) states: "This healing cannot affect creatures...of extra-planar origin." The 6th-level Wizard death spell "does not affect...creatures from planes other than the Prime Material." Clearly, if these rules are strictly followed, there is no way for priests to heal planar PCs (bariaur, githzerai, tieflings, aasimar, githyanki, rogue modrons or planar humans). The advice from TSR's designers was to simply ignore the rule (assume they were written by some clueless wizard - or Zeb Cook :-) DMs can interpret this how they wish: Healing and Death spells might be restricted to affecting only the 'mortal' races (ie. any creature except the 'immortal' planar races like the tanar'ri, rilmani or genies), or they might simply be allowed to work on any creature. Alternatively, a simple spell key might be required to cast one of these spells on a non-Prime (the symbol of the creature's home plane, for example).
A: Yeah. Careful reading of spell descriptions in the Player's Handbook will reveal a number of spells which don't work when cast on extra-planar creatures. That was written originally to prevent players using certain spells against aasimon, baatezu, elementals, and the like. With the Planescape rules, players can now have characters who don't hail from the Prime Material Plane.
For example, the 1st-level Priest spell cure light wounds (as well as all the other priest spells which heal damage) states: "This healing cannot affect creatures...of extra-planar origin." The 6th-level Wizard death spell "does not affect...creatures from planes other than the Prime Material."
Clearly, if these rules are strictly followed, there is no way for priests to heal planar PCs (bariaur, githzerai, tieflings, aasimar, githyanki, rogue modrons or planar humans). The advice from TSR's designers was to simply ignore the rule (assume they were written by some clueless wizard - or Zeb Cook :-)
DMs can interpret this how they wish: Healing and Death spells might be restricted to affecting only the 'mortal' races (ie. any creature except the 'immortal' planar races like the tanar'ri, rilmani or genies), or they might simply be allowed to work on any creature.
Alternatively, a simple spell key might be required to cast one of these spells on a non-Prime (the symbol of the creature's home plane, for example).
2. CHARACTERS AND MONSTERS
A: You can't. Most Planescape fans agree that the Lady doesn't need stats, and assigning her mere numbers lessens her aura of mystery and majesty. Rather than argue about this here, consider the words of Planescape creator Zeb Cook: "When I made up the Lady of Pain, there was a conscious decision among a lot of us at TSR *not* to give it stats. There's several reasons: 1) we wanted a mystery and wanted to make the point about the Planescape world that there are things that do not have answers; 2) she was cool and giving her stats and numbers robs her of that factor (we thought); 3) if we made up an answer then somebody would make up a thing to overcome her (be it designer, DM, or player) and all PS would wind up going to hell; 4) we didn't know and probably wouldn't have agreed; and 5) I didn't want to deal with letters saying 'My player killed the Lady of Pain and now runs Sigil so you can take her out of your manuals,' etc. "I honestly don't understand the need to give her stats. She does the things the DM needs her to do. Why, how, and by what rules is pointless and robs the imagination. It's like I don't understand the desire to quantify the powers or to create exact rules for how players become powers. If these things need to happen in a game, then they will and if they don't, then they won't." And that, as they say, is that(!) For a more complete explanation of the Planescape designer's reluctance to list the Lady's stats, please see this page of the Scripta Planorum: http://www.oocities.org/SouthBeach/1482/why.html See also the FAQ question: Who is the Lady of Pain?
A: You can't. Most Planescape fans agree that the Lady doesn't need stats, and assigning her mere numbers lessens her aura of mystery and majesty. Rather than argue about this here, consider the words of Planescape creator Zeb Cook:
"When I made up the Lady of Pain, there was a conscious decision among a lot of us at TSR *not* to give it stats. There's several reasons: 1) we wanted a mystery and wanted to make the point about the Planescape world that there are things that do not have answers; 2) she was cool and giving her stats and numbers robs her of that factor (we thought); 3) if we made up an answer then somebody would make up a thing to overcome her (be it designer, DM, or player) and all PS would wind up going to hell; 4) we didn't know and probably wouldn't have agreed; and 5) I didn't want to deal with letters saying 'My player killed the Lady of Pain and now runs Sigil so you can take her out of your manuals,' etc.
"I honestly don't understand the need to give her stats. She does the things the DM needs her to do. Why, how, and by what rules is pointless and robs the imagination. It's like I don't understand the desire to quantify the powers or to create exact rules for how players become powers. If these things need to happen in a game, then they will and if they don't, then they won't."
And that, as they say, is that(!)
For a more complete explanation of the Planescape designer's reluctance to list the Lady's stats, please see this page of the Scripta Planorum:
See also the FAQ question: Who is the Lady of Pain?
A: Sha'irs have a number of abilities relating to genies and the Inner Planes, and receive their spells through elemental 'familiars' called gens. Gen have a natural ability to plane shift. They can slip into the Astral from any outer plane which touches it (that's the top level of all Outer Planes), and from there make their way to the Inner Planes where they find the energy tokens needed for the sha'ir's spells. Layers of planes with no Astral connection require a little longer, as the gen must first shift to the first layer of the plane. Gen can get into Sigil through portals...though it often takes them a while to find a suitable one. To get out, they can fling themselves from the edge of the ring and bounce to a random plane (they generally hate this) or find a portal out. Sha'ir should try to keep spellcasting in the Cage to a minimum, or risk annoying their gen. The time required for a gen to gather spells is taken up mostly by the search for the correct token on the Inner Planes, rather than travel to and from these planes. It is therefore unnecessary to add time modifiers due to the sha'ir's current plane (though DMs might wish to add a couple of rounds for casting in Sigil itself). Note that spellcasting inside the fourth ring of the Outlands is impossible, as there is no Astral connection here, and the plane shift spell is too high level for the gen to use. Sha'irs are effectively unable to regain spells inside this area. They must also observe the level limits for spells in the other rings of the Outlands. The sha'ir's ability to calling the jann does not function on the Outer Planes, unless one actually happens to be living in the area (such as in Sigil). Similarly, summoning a genie is impossible, though a sha'ir could trap or bind a genie who is already in the area. The sha'ir's innate abilities to recognise genie work, resist the gen's own element, and the like remain unaffected by the outer Planes. Sha'irs are described in the Complete Sha'ir's Handbook, an Al Qadim supplement.
A: Sha'irs have a number of abilities relating to genies and the Inner Planes, and receive their spells through elemental 'familiars' called gens.
Gen have a natural ability to plane shift. They can slip into the Astral from any outer plane which touches it (that's the top level of all Outer Planes), and from there make their way to the Inner Planes where they find the energy tokens needed for the sha'ir's spells. Layers of planes with no Astral connection require a little longer, as the gen must first shift to the first layer of the plane.
Gen can get into Sigil through portals...though it often takes them a while to find a suitable one. To get out, they can fling themselves from the edge of the ring and bounce to a random plane (they generally hate this) or find a portal out.
Sha'ir should try to keep spellcasting in the Cage to a minimum, or risk annoying their gen.
The time required for a gen to gather spells is taken up mostly by the search for the correct token on the Inner Planes, rather than travel to and from these planes. It is therefore unnecessary to add time modifiers due to the sha'ir's current plane (though DMs might wish to add a couple of rounds for casting in Sigil itself).
Note that spellcasting inside the fourth ring of the Outlands is impossible, as there is no Astral connection here, and the plane shift spell is too high level for the gen to use. Sha'irs are effectively unable to regain spells inside this area. They must also observe the level limits for spells in the other rings of the Outlands.
The sha'ir's ability to calling the jann does not function on the Outer Planes, unless one actually happens to be living in the area (such as in Sigil). Similarly, summoning a genie is impossible, though a sha'ir could trap or bind a genie who is already in the area.
The sha'ir's innate abilities to recognise genie work, resist the gen's own element, and the like remain unaffected by the outer Planes.
Sha'irs are described in the Complete Sha'ir's Handbook, an Al Qadim supplement.
A: In bizarre and unpredictable ways. Basically, these three plane-touched races all indicate that one or more of the character's ancestors was some sort of planar creature. For tanar'ri, the direct descendants of unions between fiends and mortal are alu-fiends or cambions, so a Tanar'ric tiefling will have a fiendish grandparent rather than parent. Other planar races don't have such half-breeds, so an aasimar might well have an firre eladrin for a mother.
A: Wherever they like(!) If you use the training rules, you ought to spend some time considering possible locations of schools in Sigil and other major planar burgs that could provide training for adventurers. Planar churches (or Realms) like that of the Torilian power Tymora are friendly to adventurers, and would be likely candidates. Factions would also be good places to train, especially because higher-level members with similar beliefs might be able to teach younger PCs a trick or two. Finally, consider learning from planar creatures themselves: What better place to learn to be a warrior than fighting for the baatezu in the Blood War. They're always recruiting, after all!
A: The "official" answer from Monte Cook is that nobody gives a damn about lycanthropes on the planes (!) He's got a point: who'd be scared of a man who can change into a wolf in front of you when there could be a man who can change into a Balor standing behind you? Unofficial opinions expressed have included:
A: The "official" answer from Monte Cook is that nobody gives a damn about lycanthropes on the planes (!) He's got a point: who'd be scared of a man who can change into a wolf in front of you when there could be a man who can change into a Balor standing behind you?
Unofficial opinions expressed have included:
A: Any and all the DM chooses to allow. Pretty much anything from any of the AD&D campaign worlds is appropriate; after all, the Planes encompass all cultures of the Multiverse. Game mechanics-wise, DMs might have trouble with Athasian characters, as they're so much tougher than PCs from other worlds. A quick solution to this is to reduce their ability scores to the racial maximums of the "normal" AD&D rules when the characters are off their home prime. This might be explained by the lower temperature of the planes reducing performance, the will of the powers (they wouldn't want their creations shown up by denizens of a godless world, after all), or a magical effect caused by the absence of the ambient psionic energy of Athas or the Sorcerer Kings.
A: Any and all the DM chooses to allow. Pretty much anything from any of the AD&D campaign worlds is appropriate; after all, the Planes encompass all cultures of the Multiverse.
Game mechanics-wise, DMs might have trouble with Athasian characters, as they're so much tougher than PCs from other worlds. A quick solution to this is to reduce their ability scores to the racial maximums of the "normal" AD&D rules when the characters are off their home prime.
This might be explained by the lower temperature of the planes reducing performance, the will of the powers (they wouldn't want their creations shown up by denizens of a godless world, after all), or a magical effect caused by the absence of the ambient psionic energy of Athas or the Sorcerer Kings.
A: According to the rules describing the absolute restrictions on magic, nothing can overcome the negation of magic at the Spire, so the rilmani cannot use their magical powers there. However, there is (allegedly) a rule somewhere that states planar creatures can use any of their powers on their home plane (such as a succubus being able to become Ethereal on the Abyss, even though the Abyss has no Ethereal connections). Under this rule, a DM might choose to allow the rilmani some of all of their powers at the Spire. Bear in mind, however, that they'll suddenly become incredibly powerful, as even the gods lose their magical abilities at the Spire.
A: According to the rules describing the absolute restrictions on magic, nothing can overcome the negation of magic at the Spire, so the rilmani cannot use their magical powers there.
However, there is (allegedly) a rule somewhere that states planar creatures can use any of their powers on their home plane (such as a succubus being able to become Ethereal on the Abyss, even though the Abyss has no Ethereal connections). Under this rule, a DM might choose to allow the rilmani some of all of their powers at the Spire. Bear in mind, however, that they'll suddenly become incredibly powerful, as even the gods lose their magical abilities at the Spire.
Q: Can planar PCs take character kits as well as factions?
A: Yes, but it depends upon where in the planes a planar PC hails from as to which kits are most appropriate. If you're a planar dwarf from Mount Clangeddin then you're more than likely to have a kit from the Complete Book of Dwarves, for example. Planewalker characters, however, are far more likely to have one of the planewalker kits (there's one for each main character class in the Planewalker's Handbook) or a kit based on location (again, see the PWHB). You'll also find some kits from other sources fit in well with particular planes. For example, the 'clockwork mage' from the Complete Sha'ir's Handbook would be very appropriate for a planar wizard coming from Mechanus. See The Planewalker's Handbook, pp. 92-98, and also A Player's Guide to the Planes, p.14.
A: Yes, but it depends upon where in the planes a planar PC hails from as to which kits are most appropriate. If you're a planar dwarf from Mount Clangeddin then you're more than likely to have a kit from the Complete Book of Dwarves, for example. Planewalker characters, however, are far more likely to have one of the planewalker kits (there's one for each main character class in the Planewalker's Handbook) or a kit based on location (again, see the PWHB).
You'll also find some kits from other sources fit in well with particular planes. For example, the 'clockwork mage' from the Complete Sha'ir's Handbook would be very appropriate for a planar wizard coming from Mechanus.
See The Planewalker's Handbook, pp. 92-98, and also A Player's Guide to the Planes, p.14.
Q: How well can planars see portals?
A: The planar in question must concentrate for one round before he can see the aura of a portal. On a roll of 1, 2 or 3 on 1d6, he is able to see the faint glowing outline of a portal, or a roll of 1 if he's only casually observing. Obviously, if there is no portal within his field of vision, or he's looking at a shifting portal which is currently inactive, he doesn't detect one -- it's not a magic "find" type of ability, merely a different way of looking at things. The planar doesn't automatically know where the other end is. However, if he has the Portal Feel NWP (or a similar spell), he can get idea of which Plane, and maybe what layer the portal goes to - but that's all. Other spells or abilities may reveal what the key to the portal is. See The Planewalker's Handbook, p. 36 for more details.
A: The planar in question must concentrate for one round before he can see the aura of a portal. On a roll of 1, 2 or 3 on 1d6, he is able to see the faint glowing outline of a portal, or a roll of 1 if he's only casually observing.
Obviously, if there is no portal within his field of vision, or he's looking at a shifting portal which is currently inactive, he doesn't detect one -- it's not a magic "find" type of ability, merely a different way of looking at things.
The planar doesn't automatically know where the other end is. However, if he has the Portal Feel NWP (or a similar spell), he can get idea of which Plane, and maybe what layer the portal goes to - but that's all. Other spells or abilities may reveal what the key to the portal is.
See The Planewalker's Handbook, p. 36 for more details.
Q: Can petitioners re-enter the Prime Material Plane if they want to?
A: Yes, petitioners are free to leave their planes of residence. However, since if a petitioner is killed off his home plane he is forever gone and doesn't merge with his deity, the petitioner doesn't leave except on express order of his deity.
If the question you want answered ain't here (and you're tired of having to make up the answer :-), feel free to let me know about it. If it's one that I reckon should be here I'll add it, and if it's a bit more esoteric then I'll try to mail you personally with an answer of my own. For your convenience, there's a form below...
Your question: