Traits

Charge: If the unicorn moves at least 20 ft. straight toward a target and then hits it with a horn attack on the same turn, the target takes an extra 9 (2d8) piercing damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be knocked prone.

Innate Spellcasting: The unicorn's innate spellcasting ability is Charisma (spell save DC 14). The unicorn can innately cast the following spells, requiring no components:

At will: detect evil and good, druidcraft, pass without trace
1/day each: calm emotions, dispel evil and good, entangle

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

Magic Weapons: The unicorn's weapon attacks are magical.

Actions

Multiattack: The unicorn makes two attacks: one with its hooves and one with its horn.

Hooves: Melee Weapon Attack: +7 to hit, reach 5 ft ., one target. Hit: 11 (2d6 + 4) bludgeoning damage.

Horn: Melee Weapon Attack: +7 to hit, reach 5 ft ., one target. Hit: 8 (1d8 + 4) piercing damage.

Healing Touch (3/Day): The unicorn touches another creature with its horn. The target magically regains 11 (2d8 + 2) hit points. In addition, the touch removes all diseases and neutralizes all poisons afflicting the target.

Teleport (1/Day): The unicorn magically teleports itself and up to three willing creatures it can see within 5 ft. of it, along with any equipment they are wearing or carrying, to a location the unicorn is familiar with, up to 1 mile away.

Legendary Actions

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 creature's turn. Spent legendary actions are regained at the start of each turn.

Hooves: The unicorn makes one attack with its hooves.

Shimmering Shield (Costs 2 Actions): The unicorn creates a shimmering, magical field around itself or another creature it can see within 60 ft. of it. The target gains a +2 bonus to AC until the end of the unicorn's next turn.

Heal Self (Costs 3 Actions): The unicorn magically regains 11 (2d8 + 2) hit points.