Alicorn

Charge: If the Alicorn 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 Alicorn's Innate Spellcasting ability is Charisma (spell save DC 19). The Alicorn 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 Alicorn has advantage on Saving Throws against Spells and other magical effects.

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

Hooves. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 35 (8d6 + 5) bludgeoning damage.

Horn: Melee Weapon Attack: +7 to hit, reach 5 ft ., one target. Hit: 50 (8d8 + 5) piercing damage.

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

Healing Touch (3/Day): The Alicorn touches another creature with its horn. The target magically regains 123 (10d20 + 20) Hit Points. In addition, the touch removes all Diseases and neutralizes all Poisons afflicting the target.

Teleport (1/Day): The Alicorn 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 Alicorn 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 Alicorn makes one Attack with its hooves.

Shimmering Shield (Costs 2 Actions): The Alicorn creates a shimmering, magical field around itself or another creature it can see within 60 ft. of it. The target gains a +5 bonus to AC until the end of the unicorn's next turn.

Heal Self (Costs 3 Actions): The Alicorn magically regains 123 (10d20 + 20) Hit Points.