Spellcasting. Vivi is a 15th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 18, +10 to hit with spell attacks). Vivi has the following spells prepared:

• Cantrips (at-will): mage hand, prestidigitation, shocking grasp, message
• 1st level (4 slots): magic missile, shield, ray of enfeeblement
• 2nd level (3 slots): acid arrow, mirror image, blindness/deafness
• 3rd level (3 slots): lightning bolt, counterspell, haste
• 4th level (3 slots): dimension door, blinding smite, phantasmal killer
• 5th level (2 slots): cloudkill, wall of force

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

Spell Mastery. Vivi has mastered several spells, allowing him to cast them without expending a spell slot. He can cast magic missile, shield, and lightning bolt in this way.

Teleport (Recharge 5-6). Vivi can teleport up to 60 feet to an unoccupied space he can see.

Staff. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Spellblade. Vivi's staff is imbued with his magic. It deals an additional 2d6 damage of a type corresponding to the last damaging spell Vivi cast.

Phantasmal Killer. Vivi targets one creature he can see within 60 feet. The target must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. While frightened, the target's worst fears manifest as an illusion that only it can see. The target takes 7 (2d6) psychic damage at the start of each of its turns. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Vivi's Phantasmal Killer for the next 24 hours.

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

Teleport. Vivi uses his Teleport ability.

Spellblade (Costs 2 Actions). Vivi makes a melee attack with his staff.

Counter Spell (Costs 3 Actions). Vivi casts counterspell.

Vivi's Weakness (Knowledge Check): Vivi is a powerful sorcerer who draws strength from the elements. His greatest vulnerability is his reliance on his Phantasmal Killer spell. Although this spell is powerful, it requires his target to fail a Wisdom saving throw. If a character fails the saving throw, they can transmit a message to the party before succumbing to the effects. The message warns that Vivi's magic is tied to his fears, and confronting him with his own fears can weaken him. If the party can create an illusion or scenario that specifically taps into Vivi's fears, it disrupts his concentration, making it harder for him to maintain the spell, giving any future target advantage on the Wisdom saving throw. This information can be discovered through a successful Intelligence (Arcana) check with a DC of 18, emphasizing the importance of knowledge in the battle against Vivi.