Antipaladin

Dark  Sense . The presence of strong good registers on their senses like a noxious odor. As an action, the antipaladin can open their awareness to detect such forces. Until the end of their next turn, they know the location of any celestial or fey within 60 feet that is not behind total cover. They know the type (celestial, fey) of any being whose presence they sense, but not its identity. Within the same radius, they also detect the presence of any place or object that has been consecrated.  They can use this feature 4 times before a long rest is needed.

Chilling Hands.  Their sinister touch can cause wounds. They have a pool of dark power that replenishes when they take a long rest. With that pool, they can inflict a total of 20 hit points of necrotic damage.  As an action, they can touch a creature and draw power from the pool to inflict a number of hit points of necrotic damage to that creature, up to the maximum amount remaining in their pool.  This feature has no effect on constructs, but can be used to heal undead.

Great Weapon Fighting. When the antipaladin rolls a 1 or 2 on a damage die for an attack with a melee weapon that they are wielding with two hands, they can reroll that die but must use the new roll.

Dark Smite. On a hit with a melee weapon, the antipaladin can use a spell slot to inflict additional necrotic damage as 1d8 per spell slot.  If the opponent is a fey or a celestial, they take an additional 1d8 of damage.

Spellcasting. The antipaladin is a 5th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 14, +6 to hit with spell attacks). The antipaladin has the following paladin spells prepared:

1st level (4 slots): wrathful smite, searing smite, thunderous smite

2nd level (3 slots): branding smite, find steed

Greatsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (2d6+3) slashing damage.