Multiattack

The oni makes two Claw or Glaive attacks, or it makes three Arcane Bolt attacks. It can replace one attack with a use of Spellcasting.

Claw (True Form Only)

_Melee Weapon Attack:_ +7 to hit, reach 5 ft., one target. _Hit:_ 13 (2d8+4) slashing damage plus 10 (3d6) force damage.

Glaive

_Melee Weapon Attack:_ +7 to hit, reach 10 ft., one target. _Hit:_ 15 (2d10+4) slashing damage, or 9 (1d10+4) slashing damage in a Medium or smaller form, plus 10 (3d6) force damage.

Arcane Bolt

_Ranged Spell Attack:_ +6 to hit, range 60 ft., one target. _Hit:_ 17 (4d6+3) force damage.

Whirling Glaive (Recharge 5-6)

The oni channels its magic into its twirling glaive, creating magical wind in a 30-foot cone. Each creature in the area must make a DC 14 STR save. On a failure, a creature takes 31 (9d6) cold damage and is pushed up to 15 feet away from the oni. On a success, a creature takes half the damage and isn't pushed.

Spellcasting

The oni casts one of the following spells, requiring no material components and using CHA as the spellcasting ability (spell save DC 14).<br>At will: _darkness_, _invisibility_ (self only)<br>1/day each: _charm_, _gaseous form_, _sleep_