Amalgamation

Shapechanger. The amalgamation can use its action to polymorph into an object or back into its true, amorphous form. Its statistics are the same in each form. Any non-magical equipment it is wearing or carrying is also transformed. It reverts to its true form if it dies.

Adhesive (Object Form Only). The amalgamation can adhere to anything that touches it. A Medium or smaller creature adhered to the amalgamation is also grappled by it (escape DC 14). Ability checks made to escape this grapple have disadvantage.

False Appearance (Object Form Only). While the amalgamation remains motionless, it is indistinguishable from an ordinary object.

Unwitting Predator (Object Form Only). The amalgamation can consume any Medium or smaller object or creature grappled by it, taking 1 turn for a Tiny object or creature, and one additional turn for each larger size of object or creature. 

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage. If the amalgamation is in object form, the target is subjected to its Adhesive trait.

Spit. Ranged Weapon Attack: The amalgamation spits out an object or weapon+5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage or 4 (1d4+3) piercing damage.

Devour. Melee Weapon Attack Against Grappled Target: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) piercing damage. If it hits, target must make a strength saving throw (save DC 14). On a failed save, target is put into an extradimensional plane of existence and can be released at the amalgamation's discretion. Every turn a creature spends in the extradimensional plane of existence after a number of rounds equal to 2 times their constitution score (minimum 1) they take 5 (1d4 + 3) psychic damage.