Unicorn

If the unicorn 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.

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

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

The unicorn's weapon attacks are magical.

3 legendary actions; one at a time at the end of another creature’s turn, regaining spent uses at the start of its turn

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

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

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

1 use per day. The unicorn magically teleports itself and up to 3 willing 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 miles away.

3 uses per day. The unicorn touches another creature. The target magically regains 11 (2d8 + 2) hit points. In addition, the touch removes all diseases and neutralizes all poisons afflicting the target.

The unicorn makes one attack with its hooves.

Costs 2 legendary 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.

Costs 3 legendary actions. The unicorn magically regains 11 (2d8 + 2) hit points.