Rapid Regrowth. At the beginning of each of the Kraathak'thuul Amalgam's turns, it regains 4d6+10 Hit Points. Mind Spikes. When the Kraathak'thuul Amalgam takes damage from any source, it deals damage to that sources controller equal to 1 psychic damage per damage die used for the attack.
Multiattack. Kraathak'thuul Amalgam makes two Tentacle attacks and one Devour attack per turn. Tentacle. Melee Weapon Attack: +6 to hit, reach 5ft., one target. Hit: 8 (1d8+2) Piercing damage. Devour. The Kraathak'thuul Amalgam attempts to devour a large or smaller sized creature whole, imposing a DC17 Strength Saving Throw and swallowing the creature on a failed save. The Kraathak'thuul Amalgam may only have 1 large, 2 medium, 4 small or 8 tiny creatures swallowed at one time. at the beginning of each of the Kraathak'thuul Amalgam's turn, creatures swallowed in this manner take 6d8 Acid damage. If the Kraathak'thuul Amalgam would die while creatures are inside its stomach they are regurgitated in an empty space within 10ft. of the Kraathak'thuul Amalgam.
The Kraathak'thuul Amalgam has 1 legendary action to impose an Intelligence Saving Throw upon a single creature that has damaged it this initiative round, dealing 2d10+5 Psychic damage on a failed save and half that amount on a success.