Trenchmouths are sentient garbage disposals. Their bulbous, rubbery, tripodic, sofa-sized bodies are essentially all snaggle-fanged mouth.
Trenchmouths sport three elongating (up to 15' each) tentacles, and the two thickest end in prehensile graspers with retractable grip-spines. The slender third has two night-vision eyes and a "brainwave radar" nodule that detects (but can't read) thoughts of intelligent beings and psionics / mental mutations in a quarter-mile radius. Trenchmouths are thereby impossible to Surprise.
When attacking at range, trenchmouths lash with both arms to smash, ensnare, or both. Grasped targets suffer 1d6 damage upon initial contact and each round thereafter, and must make a DC 15 STR check to escape. If a trenchmouth successfully snags the same target with both tentacles (during the same round, or eventually), its quarry is immediately retracted for a free bite attack. Trenchmouths are otherwise only able to chomp adjacent targets. Anyone bitten by a trenchmouth must make a DC 15 Fort Save or come down with ghastly gastro-intestinal strife (aka "trench-trots") that induces temporary 1d4 damage to STR, AGL, and STA, halved movement, and -4 to all rolls over 1d3 days.
Trenchmouths lair submerged in cesspits, sewers, landfills, junkyards, dumpsters, grease traps, and porta-johns. Accordingly, they are immune to all toxins and diseases, and Surprise foes on 1-5 on 1d6. And between their spongy mass and clinging "slimy trash coating", trenchmouths only suffer half damage from clubbing- and crushing-based attacks.
Trenchmouths speak Common, Trucker, Pervert, and the secret gurglings of ooze-dom. Ambitious trenchmouths may take up adventuring, as they are surprisingly deft for their bulk and can manipulate most weapons, tools, and artifacts.
Trenchmouth (statted for Dungeon / Mutant Crawl Classics)
Init +3; Atk tentacle bludgeon +5 melee (1d10+2) or tentacle grasp +4 melee (entangle plus 1d6 per round) or bite melee +3 (2d8 + disease); AC 16; HD 8d8+17; MV trundle 20' or float 10'; Act 2d20; SP camouflage, constriction, disease, infravision 120', mind-sense; SV Fort +13, Ref +4, Wil +10; AL C
