Magic Resistance. The death knight has advantage on saving throws against spells and other magical effects.

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

Spellcasting. The death knight is a 3th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 15, +6 to hit with spell attacks). It has the following paladin spells prepared:

1st level (3 slots): command, compelled duel, searing smite

2nd level (2 slots): hold person, magic weapon

3rd level (1 slots): dispel magic, elemental weapon

Multiattack. The death knight makes two longsword attacks.

Longsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) slashing damage, or 10 (1d10 + 5) slashing damage if used with two hands, plus 9 (2d8) necrotic damage.

Hellfire Orb (1/Day). The death knight 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 cantered on that point must make a DC 15 Dexterity saving throw. The sphere spreads around corners. A creature takes 17 (5d6) fire damage and 17 (5d6) necrotic damage on a failed save, or half as much damage on a successful one.

Parry. The death knight adds 3 to its AC against one melee attack that would hit it. To do so, the death knight must see the attacker and be wielding a melee weapon.

The Undead Knight King can take 1 legendary action, 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 Undead Knight King regains spent legendary actions at the start of its turn.

Royal Rush. Moves up to your speed without provoking opportunity attacks.

Longsword. The Undead Knight King can make one Longsword attack.