Displacer Beast

Large monstrosity, lawful evil
Armor Class 13 (natural armor)
Hit Points 85 (10d10 + 30)
Speed 40 ft.
STR
18 (+4)
DEX
15 (+2)
CON
16 (+3)
INT
6 (-2)
WIS
12 (+1)
CHA
8 (-1)
Senses darkvision 60 ft., passive Perception 11
Languages
Challenge 3 (700 XP)

Avoidance. If the displacer beast is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Displacement. The displacer beast projects a magical illusion that makes it appear to be standing near its actual location, causing attack rolls against it to have disadvantage. If it is hit by an attack, this trait is disrupted until the end of its next turn. This trait is also disrupted while the displacer beast is incapacitated or has a speed of 0.

Actions

Multiattack. The displacer beast makes two attacks with its tentacles.

Tentacle. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage plus 3 (1d6) piercing damage.

This monstrous predator takes its name from its ability to mask itself with illusion, displacing light so that it appears to be somewhere it is not.
Monster Manual
Displacer Beast