Amorphous. The stalker can move through a space as narrow as 1 inch wide without squeezing.

Blood Bond. The stalker is still connected to the blood source of its origin. If the source creature is still alive, it and the stalker can communicate telepathically through the bond. The communication is possible over any distance, though it can’t extend to other planes of existence. If the source creature dies, the stalker gains access to all its memories at the time of death and recalls them as if they were its own memories, which helps to drive and focus the stalker's enmity.

Blood Magic Form. A creature that touches the stalker or hits it with a melee attack while within 5 feet of it takes 9 (2d8) acid damage plus 5 (1d10) necrotic damage. A creature also takes this damage if it is grappling the stalker or grappled by the stalker at the start of each of the stalker's turns. Any nonmagical weapon that isn't made of adamantine that hits the stalker is disintegrated at the end of the attacker's next turn.

The stalker can eat through 1 foot of any nonmagical solid substance that isn't adamantine in 1 round.

Detect Life. The stalker can magically sense the presence of living creatures that have blood up to 5 miles away. It knows the general direction they're in by using this sense, but not their exact locations or numbers.

Dispel Susceptibility. When the stalker is targeted by dispel magic, it must make a Charisma saving throw against the caster's spell save DC. On a failed save, it takes force damage equal to 5 × the spell's level, it releases any creatures it had grappled, and its Regeneration trait doesn't function at the start of its next turn.

Fiendish Hybrid. The stalker is also a fiend.

Magic Resistance. The stalker has advantage on saving throws against spells and other magical effects.

Regeneration. The stalker regains 15 hit points at the start of its turn if it has at least 1 hit point.

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

Multiattack. The stalker makes two attacks with its pseudopod.

Pseudopod. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) bludgeoning damage plus 27 (6d8) acid damage and 16 (3d10) necrotic damage, and the target is grappled (escape DC 18).

Drain Blood. The stalker drains blood from each creature that it has grappled. If a grappled creature has blood, it must make a DC 19 Constitution saving throw. On a failed saving throw, it takes 44 (8d10) necrotic damage and it is poisoned until the end of the stalker's next turn. While poisoned in this way, a creature falls prone, drops anything it is carrying, and is incapacitated. The creature's hit point maximum is reduced by an amount equal to the necrotic damage taken, and the stalker regains hit points equal to half of the necrotic damage dealt. The reduction lasts until the creature finishes a long rest. It dies if this effect reduces its hit point maximum to 0.