Xenabsorber

Disguise. The xenabsorber has advantage on Charisma (Deception) checks to pass itself off as the type of creature it is impersonating as long as it has at least 1 trait from that creature.

Trait Mimicry. As a bonus action, a xenabsorber can take on 1 nonmagical physical trait, attack, or reaction of a beast or humanoid with a challenge rating equal to or less than its own that it has seen within the last week (see Trait Mimicry sidebar). It can have up to 5 such traits at a time, no more than two of which can be attacks. Each trait lasts until the xenabsorber replaces it with another trait as a bonus action. If the xenabsorber goes a week without exposure to a single beast or humanoid, it loses all of its traits and reverts back to its true, blue crystalline form.

Multiattack. The xenabsorber makes two melee attacks.

Slam. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (1d10 + 3) bludgeoning damage.