From publisher blurb:
This worm-like creature’s long body ends in fleshy tendrils, uncoiling like bloated serpents tipped in barbed spines, surrounding a pink, bile-stinking orifice lined with rows of inward tilted fangs. The bilecrawler (also known as a bile wyrm for the gastrula stink it gives off) makes its lair in caves and dungeons, often burrowing into such places in search of water or prey. This wyrm is the bane of most subterranean humanoid races, being clever enough to tunnel around heavily defended guard positions and into living spaces and sleeping areas to feast upon the surprised inhabitants (most of whom are usually non-combatants). Many underground races have a number of folk tales regarding these monsters, most involve the wyrms having a taste for particularly unruly children. Real bilecrawlers don’t particularly care whether their meal has been naughty or nice.
This supplement includes:
Two new monsters the Bilecrawler and the Vilecrawler
Background and history of the Bilecrawler and the Vilecrawler
Bilecrawler Counters
Initiative and Monster Cards