Bert the Vampire Spawn

Regeneration. Bert regains 15 hit points at the start of his turn if he has at least 1 hit point and isn't in sunlight or running water. If Bert takes radiant damage or damage from holy water, this trait doesn't function at the start of Bert's next turn.

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

Vampire Weaknesses. Bert has the following flaws:

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

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

Stake to the Heart. Bert is destroyed if a piercing weapon made of wood is driven into his heart, mouth or stomach.

Sunlight Hypersensitivity. The vampire takes 20 radiant damage when it starts its turn in sunlight. While in sunlight, it has disadvantage on attack rolls and ability checks.

Multiattack. Bert makes two attacks, only one of which can be a bite attack.

Claws. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 9 (1d8 + 5) slashing damage. Instead of dealing damage, the vampire can grapple the target (escape DC 14).

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one willing creature, or a creature that is grappled by Bert, incapacitated, or restrained. Hit: 8 (1d6 + 5) piercing damage plus 13 (3d8) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and Bert 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. A humanoid slain this way and then buried rises the following night as a vampire spawn under Ilese's control.