Armored Slime

Amorphous. The ooze can move through a space as narrow as 1 inch wide without squeezing.

False Appearance. While the ooze remains motionless, it is indistinguishable from an pool of mercury or piece of steel

Possess Corpse (Recharge 6). The Armored Slime disappears into an intact corpse within 5 feet of it that belonged to a Medium or smaller Humanoid or Suit of Armor (use Animated Armor statblock), The Armored Slime gains 20 temporary hit points. While possessing the corpse, the armored slime adopts the corpse's size, AC, speed, and can't use Amorphous or False Appearance. Its game statistics otherwise remain the same. The possession lasts until the temporary hit points are lost or the armored slime ends it as a bonus action. When the possession ends, the armored slime appears in an unoccupied space within 5 feet of the corpse.

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 2) bludgeoning damage and 2 (1d4) acid damage.

Slam (Possession only). Melee Weapon Attack: +5 to hit, reach 5ft, one target. Hit: 22 (4d6 + 2) bludgeoning damage