Corrupted Unicorn

Charge. If the Corrupted Unicornunicorn moves at least 20 feet 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, Chill Touch, pass without trace, cause fear

1/day each: shadow of moil, 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.

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: 6 (1d6 + 4) piercing damage and 2 (1d4) Poision damage. 

Corrupting Touch (3/Day). The unicorn touches another creature with its horn. The target takes 11 (2d8 + 2) necrotic damage. In addition, the touch target must make a DC 14 constitution save or be poisoned.

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

The unicorn 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. The unicorn regains spent legendary actions at the start of its turn.

Hooves. The unicorn makes one attack with its hooves.

Shadow Shield (Costs 2 Actions). The unicorn creates a field of darkness, magical field around itself. The target gains a +2 bonus to AC until the end of the unicorn's next turn.

Corrupting Cry(Costs 3 Actions). The unicorn lets out a tortured scream. every creature in a 30 foot radius must make a DC 14 Constitution save, on a fail the next time that creature is healed within one minute they take that much necrotic damage instead.