This creature looks like a giant gray moth with spiraling bands of red and black on its body. It has large, thin, reddish-hued wings.
Spd 10 ft., fly 40 ft. (average)
Str 21, Dex 16, Con 17, Int 6, Wis 12, Cha 10
If a hell moth grapples an opponent it can wrap a Medium or smaller creature in its wings and body and automatically deal bite damage in each round it maintains the grapple. Attacks that hit an engulfing hell moth deal half their damage to the monster and half to the trapped victim.
A hell moth that has engulfed an opponent can detonate its body in a blast of hellish fire that deals 6d10 points of fire damage to itself and the engulfed opponent (no save). (Reduce the damage dealt to the hell moth by its fire resistance.) A hell moth can immolate itself once every 3 hours (providing it survives the immolation).
Creatures within 10 feet of the hell moth when it uses this ability must succeed on a DC 17 Reflex save or take 1d8 points of fire damage as clothes and combustibles ignite. The damage continues for another 1d4+4 rounds after the hell moth uses this ability or until the fire is extinguished. The save DC is Constitution-based.
Organization solitary or flock (3–6)
The hell moth is thought to have come from another plane, though sages are not quite sure of its exact origin. The hell moth attacks living creatures that wander too close to its lair. It otherwise resembles a large moth with an 8-foot wingspan.
Hell moths wait for their prey to pass nearby before attacking. If facing multiple opponents, they attempt to bite and usually do not employ their engulfing ability. Multiple hell moths work in concert with one another against opponents. When a hell moth has successfully engulfed a foe, it sets its own body on fire in a display of self-immolation that consumes both it and its engulfed opponent.
Hell Moth from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene.