Bludgeoning. If the target is a Large or smaller creature, they are Grappled, DC13 STR to escape.

If the target is grappled, the attack instead does 2d8+10 damage.

While grappling a creature the mimic can shapeshift to envelope them. An enveloped creature is no longer grappled, but they can’t breathe, are blinded, and restrained, have total cover against attacks and other effects outside the mimic, and take 5d8 acid damage at the start of each of the mimic’s turns. When the mimic moves, the enveloped creature moves with them. Action: DC13 STR Escape.