Undying Conquerer

Aura of Conquest. Unless the undying conquerer is incapacitated, all creatures frightened of it within 30 feet of it have their speed reduced to 0 and take 10 psychic damage if they start their turn within that radius.

Dueling. When the undying conquerer is wielding a melee weapon in one hand and no other weapons, it gains a +2 bonus to damage rolls with that weapon (included in the attack).

Improved Critical. The undying conquerer's attacks deal a critical hit on a roll of 19 or 20.

Legendary Resistance (3/Day). If the undying conquerer fails a saving throw, it can choose to succeed instead.

Magic Resistance. The undying conquerer has advantage on saving throws against spells and other magical effects.

Marshal Undead. Unless the undying conquerer is incapacitated, it and undead creatures of its choice within 60 feet of it have advantage on saving throws against features that turn undead.

Scornful Rebuke. Unless the undying conquerer is incapacitated, whenever a creature hits it with an attack, the attacker takes 5 psychic damage.

Spellcasting. The undying conquerer is a 20th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). It has the following paladin spells prepared:

1st level (4 slots): armor of agathys, command, compelled duel, detect magic, wrathful smite

2nd level (3 slots): find steed, hold person, lesser restoration, spiritual weapon, zone of truth

3rd level (3 slots): bestow curse, dispel magic, fear, remove curse, revivify

4th level (3 slots): banishment, dominate beast, death ward, staggering smite, stoneskin

5th level (2 slots): banishing smite, cloudkill, destructive wave (necrotic), dominate person, geas

Special Equipment. The undying conquerer wields a sword of answering (Back Talker), wears a suit of plate, +3 armor, a belt of giant strength (storm), and a headband of intellect.

Multiattack. The undying conquerer makes four melee attacks.

Back Talker. Melee Weapon Attack: +19 to hit, reach 5 ft., one target. Hit: 18 (1d8 + 14) slashing damage, or 17 (1d10 + 12) slashing damage when using two hands, plus 36 (8d8) necrotic damage.

Conquering Presence (Recharges After a Short or Long Rest). The undying conquerer exudes magical menace. Each enemy within 30 feet of the undying conquerer must succeed on a DC 20 Wisdom saving throw or be frightened for 1 minute. If a frightened target ends its turn more than 30 feet away from the undying conquerer, the target can repeat the saving throw, ending the effect on itself on a success.

Hellfire Orb (1/Day). The undying conquerer hurls a magical ball of fire that explodes at a point it can see within 120 feet of it. Each creature in a 20-foot-radius sphere centered on that point must make a DC 20 Dexterity saving throw. The sphere spreads around corners. A creature takes 42 (12d6) fire damage and 42 (12d6) necrotic damage on a failed save, or half as much damage on a successful one.

Counterattack. while the undying conquer is holding Back Talker, it can use its reaction to make one melee attack with it against any creature in its reach that deals damage to it. It have advantage on the attack roll, and any damage dealt with this special attack ignores any damage immunity or resistance the target has.

Parry. The undying conquerer adds 7 to its AC against one melee attack that would hit it. To do so, the undying conquerer must see the attacker and be wielding a melee weapon.

The undying conquerer 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 undying conquerer regains spent legendary actions at the start of its turn.

Melee Attack. The undying conquerer makes a melee attack.

Cast Spell. The undying conquerer casts a spell with a casting time of one action.

Move. The undying conquerer moves up to its movement speed without provoking opportunity attacks.