Black Unicorn

Charge. If the black 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.

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

At will: detect evil and good, druidcraft, pass without trace

1/day each: fear, dispel evil and good, entangle

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

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

Aura of Desecration. The black unicorn marches from battle to battle, seeking out violance or serves as a heavy cavalry under an evil thayan drow or red wizard instead of guarding ancient ruins and verdant groves. Because of this the black unicorn has a supernatural and unholy aura around 120 feet of it in the place of Lair Actions.
Dishallowed by the creature's hellish presence, the area around the black unicorn might include any of the following magical effects:

• Every creature with evil alignment gains Advantage on their Intimidation checks within the aura.
• When a good-aligned creature casts a spell or uses a magical effect that causes another creature to regain hit points, the target can regain only half of the hit points rolled for the spell or effect.
• When a spell or effect would remove any curse from a good-aligned creature, the curse has a 50% chance to be sustained on that creature anyway.
• Undead creatures are more resilient under the black unicorn's aura; they have advantage on Constitution saving throws in the area.

If the black unicorn dies, these effects end immediately.

Multiattack. The black 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.

Agonizing Touch (3/Day). The black unicorn touches another creature with its horn. The target magically takes 11 (2d8 + 2) points of necrotic damage. In addition, the touch bestows a disease or a poison to the target, if the target fails on a DC 15 Constitution saving throw.
If the target fails on the saving throw, choose one or roll a d10 on the following chart to determine the effect randomly (descriptions: DMG 257 - 258):

1. - Pale Tincture (poison)
2. - Sewer Plague (disease)
3. - Assassin's Blood (poison)
4. - Serpent blood (poison)
5. - Cackle Fever (disease)
6. - Essence of Ether (poison)
7. - Oil of Taggit (poison)
8. - Sight Rot (disease)
9. - Drow Poison (poison)
10. - Torpor (poison)

A creature can't be affected with the same disease or poison twice in this way.

Teleport (1/Day). The black 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 black 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 black unicorn regains spent legendary actions at the start of its turn.

Hooves. The black unicorn makes one attack with its hooves.

Dark Blessing (Costs 2 Actions). The black unicorn creates a dark, ghastly shroud around itself or another creature it can see within 60 feet of it. The target gains a +2 bonus to its damage rolls as necrotic damage until the end of the unicorn's next turn.

Dark Absorption(Costs 3 Actions). Every creature within 30 feet of the black unicorn and are hostile to it, must succeed on a DC 15 Constitution saving throw, or take 1d8+1 necrotic damage. At the same time, the black unicorn magically regains hit points equal to the necrotic damage dealt by the Dark Absorption.