Undead fortitude - If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5+the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead.

Regeneration. The king regains 10 hit points at the start of its turn if it has at least 1 hit point and isn’t in sunlight or running water. If the vampire takes radiant damage or fire damage, this trait doesn’t function at the start of the king's next turn.

Multiattack. King makes three attacks with his scimitar or three attacks with his special hand-crossbow.

Scimitar. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 7 (1d6+4) slashing damage. 

Special Hand-Crossbow. Ranged Weapon Attack: +7 to hit, range 40/80 ft., 1 target. Hit: 7 (1d6+4) piercing damage.

Parry. The king adds 2 to its AC against one melee attack that would hit it. To do so, the king must see the attacker and be wielding a melee weapon.