Vald

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

Avoidance. If Vald is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Spellcasting. Vald is a 20th-level spell caster. His spellcasting ability is Charisma (spell save DC 19, +11 to hit with spell attacks). He has the following spells prepared:

1st level (4 slots): command, hex

2nd level (3 slots): crown of madness, locate object, shatter

3rd level (3 slots): dispel magic, counterspell

4th level (3 slots): locate creature, summon greater demon

5th level (3 slots): danse macabre

6th level (2 slots): flesh to stone, mass suggestion

Multiattack. Vald fires up to 4 motes if crown of stars is active, and makes 2 attacks with his rusted sword.

Rusted Sword. Melee Weapon Attack:  +12 to hit, reach 5 ft., one target. Hit: 8 (1d6 + 5) slashing damage, and 14 (4d6) acid damage. The target takes the same amount of acid damage at the end of each its turns, repeating the save after taking the damage. On a success, the acid damage stops.

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

Flare. Vald casts lightning bolt.

Constellation (Costs 2 Actions). Vald casts steel wind strike.

Falling stars (Costs 2 Actions). Vald casts crown of stars.