An amorphous ambush predator that lies flat and mimics stone floors

A Trapper is an amorphous ambush predator which lies in wait of prey in dark underground places such as caves or dungeons; one literally lies flat and pretends to be the floor. They are able to alter their surface coloration and texture to resemble virtually any kind of natural or cut stone, allowing one to fool onlookers and thus gain surprise on 1-5 on 1d6. Common ploys for a trapper are to form part of its body into a "hump" or other protrusion that might be mistaken for a chest, or to present the appearance of a hole or displaced stone that might cover either a treasure or the entrance to some small creature's lair; any of these methods might be used to lure intelligent creatures onto the trapper. A trapper can cover an area equal to 40 square feet per hit die; thus, a 10 hit die trapper can cover 400 square feet, or up to a 20- by 20-foot room. It is when potential victims are standing on its surface that the trapper attacks, rolling itself up around them and crushing them. A 9 HD trapper can entrap at most 2 normal-sized characters (or twice that many small characters); a 10 HD one can entrap 3 such characters, an 11 HD one can entrap 4, and a 12 HD one can entrap up to 5.

An amorphous ambush predator that lies flat and mimics stone floors

Trappers are underground predators, chameleon-like creatures with flat bodies like a manta ray. They are roughly square in shape, about 20-ft by 20-ft in size (larger and smaller trappers, with proportionally higher or lower hit dice have been encountered), but can alter their dimensions to a considerable degree. These dangerous creatures lie flat on dungeon floors, waiting for prey to step onto them. While waiting in this manner, trappers are viurtually indistinguishable from the surrounding floor, 95% likely to be completely undetectable without the use of magic. When potential prey steps onto the trapper, the monster whips upward to enfold all creatures standing on it. The trapper's stone-hard skin and powerful muscles are deadly. Victims enfolded in the trapper cannot use weapons and will suffocate in 6 rounds. Moreover, before suffocating, victims will suffer 4hp damage per round plus 1 hp per point of armour class. As noted above, trappers take half damage from fire and cold, and no damage at all from such attacks if the monster is entitled to a saving throw and succeeds.