Wyrm

Wyrms are large serpent-like creatures able to breathe fire and strike from underground.

Individual wyrms are summoned by the Awaken Wyrm power, available to the Goblin and Mordor factions.

Their exact name and depiction do not originate from J.R.R. Tolkien's writings - they are based off of the Were-worms alluded to once in The Hobbit.