Apophis, Harbinger of Chaos

Acidic Blood. When Apophis takes piercing or slashing damage, each creature within 5 feet of Apophis takes 14 (4d6) acid damage.

Immutable Form. Apophis is the philosophical ideal Hydra. It is immune to any spell or effect that would alter its form.

Legendary Resistance (4/Day). If Apophis fails a saving throw, it can choose to succeed instead.

Multiple Heads. Apophis has nine heads. While it has more than one head, Apophis has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, or knocked unconscious.

Whenever Apophis takes 40 or more damage in a single turn, one of its heads dies. If all its heads die, Apophis dies.

At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken 40 or more fire damage since its last turn. Apophis regains 20 hit points for each head regrown in this way.

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

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

Multiattack. Apophis makes as many bite attacks as it has heads.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 18 (2d10 + 7) piercing damage.

Stomp. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage.

Tail. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 18 (2d10 + 7) bludgeoning damage. If the target is a creature, it must succeed on a DC 21 Strength saving throw or be pushed up to 20 feet away from Apophis.

Breath Weapon (Recharge 5–6). The Apophis exhales a blast of energy in a 300-foot cone. Each creature in that area must make a DC 26 Dexterity saving throw. On a failed save, the creature takes 78 (12d12) acid damage. On a successful save, the creature takes half as much damage.

Apophis 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. Apophis regains spent legendary actions at the start of its turn.

Detect. Apophis makes a Wisdom (Perception) check.

Tail Swipe. Apophis makes a tail attack.

Trampling Charge (Costs 3 Actions). Apophis moves up to 60 feet in a straight line and can move through the space of any creature Huge or smaller. The first time it enters each creature’s space during this move, it can make a stomp attack against that creature.