Multiattack

The Yaga goo makes two pseudopod attacks. When its Foul Transit is available, it can use Foul Transit in place of one pseudopod attack.

Pseudopod

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage plus 3 (1d6) necrotic damage.

Foul Transit (Recharge 4-6)

The goo teleports to an unoccupied space it can see within 50 feet, leaving behind a wretched puddle in the space it previously occupied. A creature within 5 feet of the space the goo left must succeed on a DC 16 Constitution saving throw or take 10 (3d6) necrotic damage and become poisoned until the end of its next turn. The first time a creature enters the puddle's space or if a creature starts its turn in the puddle's space it takes 10 (3d6) necrotic damage and is poisoned. The puddle lasts for 1 minute or until the goo that created it is killed.