Lich's Blood

It looks like a puddle of blood that has come alive, seeping and dripping slowly across the floor in search of wizards and magic items. The very first one killed its own creator, then crept off swearing revenge on every wizard it could find.

It tries to engulf a spellcaster, pouring into his mouth and nose. After one successful hit no further attack rolls are needed: the victim suffocates for 1d4 damage each round and must save vs. spell every round or forget 1d4 memorized spells, highest levels first. Once his spells are gone it keeps clinging to wring out every trace of magic, letting go only five rounds after the last spell is drained.

Being liquid, it ignores weapons, and any spell cast at it is soaked up harmlessly. Only mundane fire, nonmagical acid or starving it of magic can kill it. Dispel magic deals 1d6 damage per caster level, and an anti-magic shell destroys it outright.

Each lives alone. It needs magic the way people need water, and can survive forever wrapped around a permanent magic item, feeding on its emanations. A wizard is far better fare, and it never passes up the chance to attack one. After draining any wizard above 5th level, it splits like an amoeba, and the two go their separate ways. It can live anywhere but prefers dark underground places; sunlight hurts it without causing damage.

Nothing hunts lich's blood, and it hunts nothing but spellcasters.