Blood Puppet

Blood Form. The elemental can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Freeze. If the elemental takes cold damage, it partially freezes; its speed is reduced by 20 feet until the end of its next turn.

Blood Letting. The elemental loses HP at the end of every turn by an amount equal to the hit dice of the creature it was formed from.

Multiattack. The puppet makes two slam attacks.

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Blood Drain (Recharge 4-6). Each creature with blood in the puppet's space must make a DC 15 Constitution saving throw. On a failure, a creature takes 10 (3d6) necrotic damage, their hit point maximum is reduced by that amount until they take a long rest, and the Elemental is healed for half as much damage dealt.