Large aberration, chaotic neutral

Armor Class 14 (natural armor)
Hit Points 104 (16d10 + 16)
Speed 10 ft.

17 (+3) 15 (+2) 12 (+1) 13 (+1) 12 (+1) 14 (+2)

Skills Athletics +6, Stealth +5
Damage Resistances fire, cold
Senses blindsense 60 ft., passive Perception 11
Languages Deep Speech, Deep Speech
Challenge 5 (1,800 XP)


  • Amorphous. The trapper can move through space as narrow as 1-inch-wide without squeezing.
  • Damage Transfer. While engulfing a creature, the trapper takes only half the damage dealt to it rounded down), and the engulfed creature takes the other half.
  • False Appearance. While the trapper remains motionless, it is indistinguishable from the surrounding floor.


  • Smother. Melee Weapon Attack: +6 to hit, reach 5 ft., one Medium or smaller creature. Hit: The creature is grappled (escape DC 16). Until this grapple ends, the target is restrained, blinded, and at risk of suffocating, and the trapper can’t smother another target. Also, at the start of each of the target’s turns, the target takes 10 (2d6 + 3) bludgeoning damage.


Trappers are clever monsters found only in caves, caverns, and other dark places. They prefer a subterranean habitation to all others. They shape their flat bodies to conform to the floor surface of their abode. Being of a consistency almost as hard as stone, trappers are nearly impossible to detect (95%) by any normal means. Usually, a trapper will wait until its prey is near its center (where it often creates a protuberance which resembles a chest or box) and then suddenly closes itself upon the unsuspecting victims. The trapper then crushes them doing a base damage of 4 plus the armor class of the victim per turn of crushing. Those entrapped are unable to use weapons, for the great musculature of the trapper prevents it. Prey will be smothered in 6 melee rounds regardless of the damage sustained. It must be killed or faced with certain death to make it free its prey.

Its treasure is kept beneath it. Trappers are resistant to fire and cold (half or no damage).

Lurker Below. Trappers are amorphous in form, so they can shape themselves to the form of the floors of the places they choose to await prey. A typical trapper can cover on area of up to 400 square feet, and giant specimens can cover as much as 600 square feet. The trapper also has the advantage of being able to alter its coloration to blend with the color of the floor or ground upon which it rests.

Section 15: Copyright Notice

Ultimate Treasury (5E) © 2023, Legendary Games; Authors: Jason Nelson, Loren Sieg, Pedro Coelho, Matt Goodall, Linda Zayas-Palmer, Thurston Hillman, Jeff Ibach, and Alex Augunas

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