Aura of Darkness. Yveltal exudes an aura of death that seems to bring more pain. All necrotic damage deals an additional 2d4 damage.

Multi Attack. Makes 3 Claw Attacks.

Claw. Melee Weapon Attack: +5 to hit, reach 10 ft., 1 target. Hit: 9 (2d4 + 5) slashing and 5 (1d8 + 1) necrotic damage.

Dark Pulse. Ranged Magic Attack: +8 to hit, range 40/120 ft., 1 target. Hit: 14 (7d4 ) necrotic damage. On a hit, roll a d10. On a 10, the creature attacked is stunned until the beginning of Yveltal’s turn. 

Dragon Rush. (9 turn recharge) Yveltal flies upward before crashing down on a selected spot. Any creature within a 10ft radius of the point that isn’t Yveltal must roll a DEX save (DC 15). On a fail, that creature takes 3d10 force and 3d4 necrotic damage. On a success, nothing happens.

Heat Wave. (9 turn recharge)Yveltal brings forth burning winds. Any creature in a 30 ft cone in front of Yveltal must make a CON save (DC 18). On a fail, the creature takes 3d10 fire damage and 1d12 necrotic damage. On a success they only take half the fire damage.

Taunt. (5 times a day) Yveltal chooses a creature and messes with their mind. The Creature must make an INT save (DC 16). On a fail, the Creature can only take the Attack action next turn. On a success, nothing happens.

Sacrificial Power. Yveltal can take 1d12 damage to deal an extra +10 on its next attack.

Sucker Punch. If a creature makes a melee attack on Yveltal, it can make a Claw Attack.

At quarter hit points, Yveltal can use it’s legendary action.

Oblivion Wing (Costs 3 Actions). Yveltal chooses up to 5 creatures to attack with beams of crimson light. The creature takes 10d10 necrotic damage. Yveltal heals 5d10 hit points. Any creature reduced to 0 hit points from the attack will suffer instant death, their body and all non magical equipment is turned to stone.