Corrupted Xeno-Symbiote (The Thing)

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

Flight. The corrupted xeno-symbiote freely grow wings from its ooze-like flesh, granting it a flying speed equal to its walking speed.

Swim. The corrupted xeno-symbiote freely grows webbed limbs and fins, granting it a swimming speed equal to its walking speed.

Shapechanger. The corrupted xeno-symbiote can use its action to polymorph into a Small, Medium or Large creature (expect for constructs and undead) it has seen, or back into its true form. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Ambusher. The corrupted xeno-symbiote has advantage on attack rolls against any creature it has surprised.

Surprise Attack. If the corrupted xeno-symbiote surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 4d6 damage from the attack.

Amorphous. The corrupted xeno-symbiote can squeeze through a space as narrow as 1 inch wide, provided it is wearing and carrying nothing. It has advantage on ability checks it makes to initiate or escape a grapple.

Unusual Nature. The corrupted xeno-symbiote doesn’t require sleep, food, air or water. 

Mitosis. Once every seven days, the corrupted xeno-symbiote will physically split into two separate corrupted xeno-symbiotes of the same level, hit points and abilities. This process of splitting and dividing takes 3 hours and for this duration the corrupted xeno-symbiote is incapacitated. 

Xeno Spores. If the corrupted xeno-symbiote ends its turn within 5ft of a restrained or grappled creature, the corrupted xeno-symbiote can force the creature to make a DC 16 Constitution saving throw as it releases spores from openings on its body; creatures that are undead or constructs are unaffected. If the saving throw fails by 5 or more, the creature is instantly rendered unconscious. Otherwise, a creature that fails the save is now stunned until the end of the corrupted xeno-symbiote's next turn. Stunned and unconscious creatures have disadvantage on Constitution saving throws against corrupted xeno-symbiote's xeno spores.

A creature that is unconscious may repeat the save at the end of each of their turns to awaken. After two consecutive saving throw failures, the xeno spores successfully implant within the target creature's body and a small xenomorph embryo (AC 10, HP 2, immunity to acid) grows within the creature's chest in 1d4 hours; afterward, the xenomorph embryo will burst out of creature's chest and instantly kill it within 1d6 hours (xenomorph embryo can be removed surgically before this with a DC 18 Medicine skill check).

Cryogenic Dormancy. Although the corrupted xeno-symbiote is vulnerable to cold damage, if its hit points are reduced to 0 or lower by cold damage, instead of dying, the corrupted xeno-symbiote instead regains half of hit points within 10 minutes and remains alive but unconscious so long its body remains frozen. 

Multiattack. The corrupted xeno-symbiote makes two pseudopod melee attacks and one parasyte projectile ranged attack.

Pseudopod. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit:  5d4 + 6 bludgeoning damage plus 1d6 acid damage. Target creature must make a Strength saving throw DC 19 or else become restrained by the thick goo-like flesh of the pseudopod, the target creature is restrained until the end of the creature's next turn.  

Parasyte Projectile. Ranged Weapon Attack: +11 to hit, 50 ft range, one target. Hit: 2d4 + 6 piercing damage. Additionally, if the attack hits, the parasyte worm that dealt damage automatically uses its Consume Limb feature on the target creature.

Pseudopod Impale. Melee Weapon Attack: +11 to hit, reach 20 ft. Hit:  3d6 + 6 piercing damage and if the target is a creature, it is grappled (escape DC 19 Strength saving throw). Until this grapple ends, the target takes 3d8 piercing damage at the start of each of its turns. The corrupted xeno-symbiote can grapple only one creature at a time.

Newborn Symbiosis. As a bonus action, the corrupted xeno-symbiote can attach a newborn symbiend to an aberration, beast, fey, dragon, humanoid, or monstrosity within 15 feet that is unconscious or dying (still in death throws). The newborn symbiend enters the flesh and body and integrates itself within the creature's internal organs and nervous system, however the symbiend is in full control of the creature and the two creatures effectively become one until the host is killed, the symbiend chooses to detach itself, or the symbiend is removed with a medical procedure (usually requiring a successful DC 24 Medicine skill check). The host requires twice as much food and water each day in order to maintain the combined metabolism of its body and the symbiend's. 

Acid Blood. When the corrupted xeno-symbiote takes bludgeoning, piercing, or slashing damage, each creature within 5 feet of the corrupted xeno-symbiote takes 4d8 acid damage.

The corrupted xeno-symbiote can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The corrupted xeno-symbiote regains spent legendary actions at the start of its turn.

Infectious Mimicry (Costs 2 Actions). The corrupted xeno-symbiote makes a single pseudopod impale melee attack against a target creature; if the creature is hit with this attack, the creature must make a DC 16 Constitution saving throw or else be rendered unconscious until the start of its next turn. The Constitution saving throws DC increases to DC 18 if the target creature is not at its total hit points.

At the start of the target creature's turn, if it has less than half of its total hit points and failed its previous saving throw, it must make a final Constitution saving throw; on a failure the creature dies immediately and becomes a corrupted xeno-symbiote after 1d4 hours.

Status Promotion. The corrupted xeno-symbiote targets a creature it can see that has taken damage from the previous attacks of the corrupted xeno-symbiote. The hostile cells from the corrupted xeno-symbiote attempt to due further harm to the wounded creature; that creature must make a DC 13 Wisdom saving throw or else it takes 4d4 necrotic damage and receives a point of exhaustion. 

Pseudopod. The corrupted xeno-symbiote makes a single pseudopod melee attack.