Medium Fey, lawful neutral
Armor Class 20 (plate and shield)
Hit Points 171 (18d8+90)
Speed walk +30
Challenge 11
Saving Throws dex +4, wis +8
Skills arcana +7, history +7, athletics +10, perception +8
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities cold, lightning, poison
Condition Immunities exhaustion, paralyzed, poisoned
Senses Devil sight 120ft, passive Perception 18
Languages Celestial, Common, Infernal; telepathy 100 ft.
Black Night. The horseman can see perfectly in normal and magical darkness
Innate Spellcasting. the horseman is a 12th-level spellcaster. Its spellcasting ability is Charisma (save DC 16, +8 to hit with spell attacks). It can innately cast the following spells, requiring no material components: at will: ray of frost 1/day each: dimension door, fire shield, haste, slow 2/day: darkness 3/day each: ethereal jaunt, phantom steed (appears as a horse colored appropriately to the horseman), plane shift (self and steed only)
Magic Resistance. The horseman has advantage on saving throws against spells and other magical effects.
Peerless Rider. Any attacks directed at the horseman's mount targets the horseman instead. Its mount gains the benefit of the rider's damage and condition immunities, and if the horseman passes a saving throw against an area effect, the mount takes no damage.
Quick Draw. The horseman can switch between wielding its lance and longsword as a bonus action.
Multiattack. The horseman makes three attacks with its lance or longsword. It can use Temporal Strike with one of these attacks when it is available.
Lance. Melee Weapon Attack: +10 to hit, reach 10 ft. (disadvantage within 5 ft.), one target. Hit: 12 (1d12 + 6) piercing damage.
Longsword. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) slashing damage.
Temporal Strike (recharge 5-6). When the horseman strikes a target with a melee attack, in addition to taking normal damage, the target must succeed on a DC 17 Constitution saving throw or instantly age 3d10 years. A creature that ages this way has disadvantage on attack rolls, ability checks, and saving throws based on Strength, Dexterity, and Constitution until the aging is reversed. A creature that ages beyond its lifespan dies immediately. The aging reverses automatically after 24 hours, or it can be reversed magically by greater restoration or comparable magic. A creature that succeeds on the save is immune to the temporal strike effect for 24 hours.
Source: Tome of Beasts · OGL/Open