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.
Multiattack. The undead knight makes two longsword attacks.
Longsword. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.
Description
Black Knights are the reanimated corpses of long dead champion knights. Even as soulless husks, they retain the skills and martial prowess they had in life, and obediently follow the orders of the necromancer who animated them. When not carrying out a task, they simply stand still and stare into space. Dark wizards favour these undead, as they make ideal guards and soldiers. Black knights are usually dressed in tattered black surcoats and capes, which help mask their decaying bodies.