Vampiric Knight

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

Spider Climb. The vampiric knight can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Turn Resistance. The vampiric knight has advantage on saving throws against effects that turn Undead.

Unusual Nature. The vampiric knight doesn't require air.

Vampire Weaknesses. The vampiric knight has the following flaws:

Forbiddance. The vampiric knight can't enter a residence without an invitation from one of the occupants.

Harmed by Running Water. The vampiric knight takes 20 acid damage when it ends its turn in running water.

Stake to the Heart. The vampiric knight is destroyed if a piercing weapon made of wood is driven into its heart while it is incapacitated in its resting place.

Multiattack. The vampiric knight makes two Impaling Longsword attacks. It can replace one Impaling Longsword attack with one Bite attack.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one willing creature, or a creature that is grappled by the vampiric knight, incapacitated, or restrained. Hit: 8 (1d6 + 5) piercing damage, plus 14 (4d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and the vampiric knight regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.

Impaling Longsword. Melee Weapon Attack: +9 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 13 (3d8) necrotic damage. If the target is a Medium or smaller creature, it is impaled on the vampiric knight's longsword, being grappled by the vampiric knight (escape DC 17). Until the grapple ends, the target is restrained, takes 13 (3d8) necrotic damage at the start of each of its turns, and the vampiric knight can’t make Impaling Longsword attacks against other targets.

Channel Corruption (Recharge 5-6). Each creature other than Constructs or Undead within 20 feet of the vampiric knight must make a DC 17 Constitution saving throw, taking 42 (12d6) necrotic damage on a failed save, or half as much damage on a successful one.

Shield Block. When a creature the vampiric knight can see attacks a target other than the vampiric knight that is within 5 feet of it, the vampiric knight imposes disadvantage on the attack roll.