In their grim and blood-spattered lairs, necromancers experiment with skeletal remains the way chefs tinker with recipes. Many wizards produce variations on the animated skeleton, and undead legions boast their own skeletal officers, specialists, and fearsome elite soldiers.

Undead Nature. A skeleton doesn’t require air, sustenance, or sleep.

Any living or dead humanoid can become a shadow symbiote thrall. Its challenge rating increases by 2. A creature retains all its statistics except as noted below.

Type. If the thrall is a dead humanoid, its type becomes undead.

Damage Resistances. The thrall gains resistance to acid, cold, fire, lightning, and thunder damage and damage from nonmagical weapons.

Damage Immunities. The thrall gains immunity to necrotic and poison damage.

Blindsight. The thrall gains blindsight out to a range of 120 feet.

Heart of Darkness. Creatures within 30 feet of the thrall have the range of their darkvision reduced by 60 feet, to a minimum of 0.

Telepathy. The thrall gains telepathy out to a range of 30 feet.

If the thrall’s character level or challenge rating is 2 or higher, it can take the following additional bonus actions:

Shadow Tendril. Melee Spell Attack: proficiency bonus + Charisma modifier to hit, reach 15 ft., one target. Hit: 14 (4d6) necrotic damage, and any light source the target wears or carries is suppressed until the end of the thrall’s next turn.

Snuff Light. The thrall magically extinguishes nonmagical light sources within 30 feet.

A shadow symbiote is a translucent, intelligent ooze the color of smoke. Although it can survive alone in darkness, it prefers to lurk within its favorite hiding place: an intelligent humanoid.

Coaxing Charm. A shadow symbiote can’t speak aloud but it can communicate telepathically. It uses this ability to deceive creatures into letting it form a symbiotic bond with them. To do so, it extols the benefits it grants: telepathy, the ability to see in the dark, supernatural control of shadows, and all the information it has gathered in its previous life. Shadow symbiotes frequently lie, claiming to be friendly ghosts or magic items that require attunement. If they are unable to convince a victim to enter a symbiotic relationship, they do so by force.

Strange Symbiosis. A shadow symbiote’s strange, insubstantial form can be absorbed through a creature’s skin. Once inside a creature, the symbiote is virtually immune from harm, although it can still be burned by radiant energy that harms its host. While it doesn’t control its host’s actions, it exerts a constant telepathic pressure, urging the host to do its bidding. A humanoid that has been a host for a significant length of time usually acts as one with the symbiote.

Dead Shell. If it needs to, a shadow symbiote can possess a dead humanoid. It controls the corpse’s body directly instead of telepathically offering advice and instructions. A symbiote controlling a corpse looks for the first opportunity to leave that body in exchange for a living one