Multiattack. The crabsquid either makes two claw attacks or makes one claw attack and then its eviscerate attack.

Claw. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 27 (4d10 + 6) bludgeoning damage, and the target is grappled (escape DC 15). The crab has two claws, each of which can grapple only one target.

Eviscerate.  Melee Weapon Attack: +10 to hit, reach 5 ft., one target that the crabsquid has grappled. Hit: 22 (3d12 + 3) slashing damage, and the target's Constitution score is reduced by 1d4. The target dies if this reduces its Constitution to 0. Otherwise, the reduction lasts until the target finishes a short or long rest.

Aethernull Pulse (Recharge 5-6). The crabsquid releases a pulse of antimagic, as in the antimagic field spell, in a 40-foot diameter sphere centred on itself. This effect lasts until the end of the crabsquid's next turn. This effect also drains aetherium crystals of their arcane power, and any items powered by them are depleted of power until the crystal is replaced.