Blood Pool Mimic

Shapechanger. The mimic can use its action to polymorph into an blood pool or back into its true, amorphous from. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies 

Adhesive (Blood Pool Form Only) . The mimic adhesive to anything that touches it. A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 13). Ability checks made to escape this grapple has disadvantage. 

False Appearance (Blood Pool Form Only).  While the mimic remains motionless, it is indistinguishable from an ordinary blood pool.

Grappler. The mimic has advantage on attack rolls against any creature grappled by it 

Amorphous (Blood Pool Form Only). The blood pool can move through a space as narrow as 1 inch wide without squeezing 

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

Split. When a blood pool that is medium or larger is subjected to lightning or slashing damage,it splits into two new blood pool if it has at least 10 hit points. Each new blood pool has hit points equal to half the original blood pool's, rounded down. New blood pools are one size smaller than the original blood pool.