Undead Fortitude.

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

Unusual Nature.

The skeletal knight doesn't require air, food, drink, or sleep.

Actions

Multiattack.

The skeletal knight makes three Enervating Blade or Throwing Axe attacks in any combination.

Enervating Blade.

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 15 (3d6 + 5) necrotic damage, and if the target is a creature, it can't regain hit points until the start of the skeletal knight's next turn.

Throwing Axe.

Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 14 (2d8 + 5) slashing damage.

Skeletal Knight