Basil Nydra

Multiple Heads. Basil starts with five heads. While he has more than one head, Basil has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.-

Whenever Basil takes 60 or more damage in a single turn, one of his heads dies. If all his heads die, Basil dies.

At the end of its turn, Basil grows two heads for each of its heads that died since its last turn, unless it has taken radiant damage since its last turn. Basil regains 40 hit points for each head regrown this way.

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

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

Many Eyes. Basil is immune to being flanked unless blinded.

Multiattack. Basil makes as many Bite attacks as he heads.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) damage of a type chosen by the dracohydra: acid, cold, fire, lightning, or poison.

Prismatic Breath (Recharge 4–6). Basils heads exhale a single breath of multicolored energy in a 60-foot cone. Each creature in that area must make a DC 17 Dexterity saving throw. On a failed save, the creature takes 33 (6d10) damage of a type chosen by Basil: acid, cold, fire, lightning, or poison. On a successful save, the creature takes half as much damage.

Spell Casting (recharge 1-3):  As an action Basil can cast Storm Sphere

Bite. and has as many reaction as he has heads

Basil 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. Basil regains spent legendary actions at the start of his turn.

Attack. Basil makes one Claw or Tail attack.

Furious Bite (Costs 2 Actions). Basil makes one Bite attack. If the attack hits a creature, the target must succeed on a DC 27 Wisdom saving throw or become Frightened of Basil until the end of its next turn.