Ancient Dracohydra

Legendary Resistance (3/Day). If the dracohydra fails a saving throw, it can choose to succeed instead.

Multiple Heads. The dracohydra has five heads. While it has more than one head, the dracohydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever the dracohydra takes 30 or more damage in a single turn, one of its heads dies. If all its heads die, the dracohydra dies.

At the end of its turn, the dracohydra grows two heads for each of its heads that died since its last turn, unless it has taken radiant damage since its last turn. The dracohydra regains 10 hit points for each head regrown this way.

Reactive Heads. For each head the dracohydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Wakeful. While the dracohydra sleeps, at least one of its heads is awake.

Multiattack. The dracohydra makes as many Bite attacks as it has heads.

Bite. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 17 (2d10 + 6) damage of a type chosen by the dracohydra: acid, cold, fire, lightning, or poison.

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 17 (2d10 + 6) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be pushed up to 20 feet away from the dracohydra.

Prismatic Breath (Recharge 4–6). The dracohydra’s heads exhale a single breath of multicolored energy in a 90-foot cone. Each creature in that area must make a DC 20 Dexterity saving throw. On a failed save, the creature takes 55 (10d10) damage of a type chosen by the dracohydra: acid, cold, fire, lightning, or poison. On a successful save, the creature takes half as much damage.

The dracohydra 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 dracohydra regains spent legendary actions at the start of its turn.

Detect. The dracohydra makes a Wisdom (Perception) check.

Tail Swipe. The dracohydra makes a tail attack.

Wing Attack (Costs 2 Actions). The dracokydra beats its wings. Each creature within 15 feet of the dracohydra must succeed on a DC 20 Dexterity saving throw or take 15 (2d8 + 6) bludgeoning damage and be knocked prone. The dracohydra can then fly up to half its flying speed.