Opieph, Dye Worm

Opieph is an alien Dye Worm, a massive species of sand-worm-like beasts that live on a desert planet.  As part of their biology, they produce a toxic chemical which is a super-drug.  Out of the gills directly, even a tiny amount is enough to be lethal to most human-sized beings.

Opieph has been moved off-world, however, because Opieph is HUGE!  It is so massive, it was disrupting the natural ecosystem, endangering production of the drug.  Because aliens are bastards, Earth was chosen as the new home.  Obviously, the chairmen thought it would be a brilliant idea (with a little chemical help) to place a titanic poisonous worm on a planet with a fragile ecosystem patrolled by equally giant monsters.  Fortuantly, Opieph is big enough to defend itself marvelously.

Opieph's head can fold up to form a giant drill, used to burrow through the earth.  A drill also tips its tail.  Its natural ranged attack is to spit out a geyser of Dye, the drug Dye Worms produce.  At such massive quantities, it can even corrode high-grade metal!