Multiattack

The sap demon makes two Slam or Lob Sap attacks. If both Slam attacks hit a Medium or smaller creature, the creature is grappled (escape DC 12).

Slam

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) bludgeoning damage plus 7 (2d6) acid damage.

Lob Sap

Ranged Weapon Attack: +4 to hit, range 20/60 ft., one target. Hit: 12 (3d6 + 2) bludgeoning damage, and the target's speed is reduced by 10 feet until the end of its next turn.

Soul Sap (Recharge 6)

One humanoid the sap demon is grappling or that is incapacitated within 5 feet of the sap demon must succeed on a DC 12 Constitution saving throw or be possessed by the sap demon. The sap demon then disappears, and the target is incapacitated and loses control of its body. The sap demon now controls the body but doesn't deprive the target of awareness. The ooze can't be targeted by any attack, spell, or other effect, except ones that restore a creature's hp maximum. The ooze retains its Intelligence, Wisdom, and Charisma and condition immunities. It otherwise uses the possessed target's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies.