Multiattack

The remorhaz makes a bite attack and then a constrict attack.

Bite

Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 16 (3d6 + 6) piercing damage plus 10 (3d6) fire damage. If the target is a Medium or smaller creature grappled by the remorhaz the target is swallowed. A swallowed creature is blinded and restrained it has total cover from attacks from outside the remorhaz and it takes 21 (6d6) acid damage at the start of each of the remorhazs turns.

If a swallowed creature deals 30 or more damage to the remorhaz in a single turn, or if the remorhaz dies, the remorhaz vomits up all swallowed creatures

Constrict

Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 16 (3d6 + 6) bludgeoning damage and the target is subjected to the remorhazs Heated Body trait. The target is grappled (escape DC 18) and restrained while grappled. The remorhaz can grapple three creatures at once.