Amphithere

Amphibious. The amphithere can breathe air and water.

Fleet of Fin. While swimming or flying, the amphithere can take the Dash or Disengage action as a bonus action.

Multiattack. The amphithere makes two attacks, one with its bite and one with its tail.

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) poison damage, and the target must succeed on a DC 14 Constitution saving throw or become poisoned for 1 hour.

Tail. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 8 (1d10 + 3) bludgeoning damage.

Poison Breath (Recharge 5–6). The amphithere exhales a blast of stinging venom in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 21 (6d6) poison damage on a failed save, or half as much damage on a successful one. A creature reduced to 0 hit points by this attack remains stable but is poisoned for 1 hour, even after regaining hit points. If a creature has total cover from the amphithere, it is not affected by the breath attack.

The amphithere can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The amphithere regains all spent legendary actions at the start of its turn.

Tail. The amphithere makes a tail attack.

Poison Breath (Costs 2 Actions). The amphithere makes a poison breath attack. It can’t use this unless its poison breath has recharged.