Illumination. The spirit sheds either dim light in a 15-foot radius, or bright light in a 15-foot radius and dim light for an additional 15 feet. It can switch between the options as an action.

Magic Resistance. The spirit has advantage on saving throws against spells and other magical effects.

Incorporeal Movement. The spirit can move through other creatures and objects as if they were difficult terrain and creatures can do the same to it. All creatures it passes through, or that pass through it, take 5 (1d10) fire damage and are pushed into the nearest empty space next to the spirit. The spirit takes 5 (1d10) force damage if it ends it turn inside an object or creature.

Undead Nature. The spirit doesn’t require air, food, drink, or sleep.

Multiattack. The spirit casts two spells.

Spellcasting. The spirit casts one of the following spells, using Intelligence as the spellcasting ability (save DC 15, +5 to hit with spell attacks):

Cantrip (at will): mage hand

1st level (3 per day each): magic missile

2nd level (2 per day each): blur, flaming sphere

3rd. level (1 per day): fireball

Arcane Defense (3/Day). When it is hit by an attack or the magic missile spell, the spirit protects itself with an invisible barrier of magical force. Until the end of its next turn, it gains a +5 bonus to AC, including against the triggering attack.