Vanan, Lord of Nightmares

Multiattack. The Xernax makes one sword of the raven attack, one shield of the panther attack, one tails attack, and one claws attack. 

Sword of the Raven. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 40 (7d10) Slashing damage and 24(4d10) Necrotic damage. 

Shield of the Panther. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 40(8d8 +4) Bludgeoning damage.

Tails. Melee Weapon Attack: +7 to hit, reach 10 ft., 2 targets. Hit: 25(7d6) Bludgeoning damage.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., 2 targets. Hit: 32(6d8) Slashing damage.

Shield. Vanan, Lord of Nightmares holds a shield with a panther emblem that can absorb and redirect spells. If Vanan succeeds on a spell save DC the spells effects is redirected at the caster. Once Vanan has done this two times his size increases and again after the next two times. Once Vanan becomes gargantuan he grows wings and can fly.

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

Claws and Tails. Vanan makes a claws attack and a tails attack.
Multiattack (Costs 2 Actions). Vanan does his multiattack action
Grow (Costs 3 Actions). Vanan's size increases.