There are 2 major cards and a concept that confuse a lot of people. They are Necrovalley, Barrel Behind the Door, and targeting effects. In order to help reduce the amount of confusion, I've made a list of cards that fit into the respective categories. I haven't listed every card made in these lists, but if a card you're curious about is not here, there's a good chance that a card with a similar effect is.

What does Necrovalley negate?

Monster Reborn
Premature Burial
Call of the Haunted
Shallow Grave
Warrior Returning Alive
Soul Release
Question
De-Fusion
Book of Life

Graverobber
Fiend Comedian
Backup Soldier
Skull Lair

Red Moon Baby
Fusioh Richie
Penguin Knight
Fiber Jar
Kycoo the Ghost Destroyer
Magician of Faith
Mask of Darkness
Dark Necrofear's first effect (remove 3 monsters from the Graveyard to Special Summon it)
Rock Spirit and any other monster Special Summoned in a similar manner


What effects can still be used when Necrovalley is active?

Black Pendant
Sword of Deep Seated
Axe of Despair
Horn of the Unicorn
Melevolent Nuzzler
Horn of Light

Rite of Spirit

Dark Necrophia - second effect (if it's destroyed, it can still equip a monster after being in the Graveyard)
Twin Headed Behemoth
Revival Jam
Witch of the Black Forest
Sangan
Mystic Tomato and the other MRL 1400's
Pyramid Turtle
Sinister Serpent (it's not on the field so the effect can't be negated by Necrovalley)
Helpoemer


What cards can Barrel Behind the Door reverse the damage of? (Barrel Behind the Door can chain to all of the below)

Tremendous Fire
Ookazi

Ring of Destruction
Ceasefire
Magic Cylinder
Attack and Recieve

Cannon Soldier
Catapult Turtle
Ameba


What can't you chain Barrel Behind the Door to?

Dark Snake Syndrome
Burning Land

Barrel Behind the Door
Destruction Wheel
Ominous Fortunetelling

Relinquished
Fire Princess
Lava Golem
Parasite Paracide


What cards have targeting effects? (The player chooses the target)

Tribute to the Doomed
Premature Burial (only once the monster is on the field)
All equip cards
Darkness Approaches
Change of Heart

Call of the Haunted (once the monster is on the field)
Blast With Chain
Ring of Destruction
Magic Cylinder
Trap Hole
Chain Destruction

Dark Necrofear
Dark Jeroid
Man Eater Bug
Penguin Soldier
Exiled Force


What cards don't have targeting effects? (cards that affect the Graveyard or monsters in the Graveyard do not target)

Monster Reborn
Dark Hole
Raigeki
Creature Swap
Insect Barrier
Messenger of Peace

Last Turn
Mirror Force
Torrential Tribute
Mirror Wall
Fairy Box
Gravity Bind
Infinite Dismissal
Bottomless Trap Hole (can be used to destroy multiple monsters is multiple monsters are summoned at the same time via Cyber Jar etc)

Cannon Soldier (there's a difference between offer as Tribute and target)
Cyber Jar
Morphing Jar #2
Fiber Jar