How Dragon Crystals are placed
dc's are loaded on random mobs when they are loaded or shortly afterwards.
(unlike all other random items, potions, orbs, and scrolls are only
loaded randomly when a mob that can carry them is killed)
The code will load new ones only when the number is low enough, around
6-12 in the game, probably closer to 6.
That means carrying a dc around lowers the chances of another being generated.
Most appear when zones are first loaded after a crash.
They cannot appear on combs, wilderness, or shopkeepers, Anything else can carry
them, INCLUDING clantown mobs. If you can peek inventory, and see invisible, you
can look for dc's... they can sometimes be stolen from a mob carrying them
This means your best chance is to peek all the mobs in a zone right after
a crash or restart... any mob killed and repopped is far less likely
to have a dc. Ideally you want to be the only person on, trigger a zone, and check
every mob in it, unfortunately this is pretty unlikely to happen anymore.