Most who are unlucky enough to encounter the infernal flotsam only get a whiff of its noisome odor; that of freshly churned earth, putrid meat, and rancid sweat. When visible, the fiendish ooze is a roiling mass of gelatinous cruor, half-dissolved body parts and clotted cancerous lumps. Human-sized scabs float across its surface, breaking apart and re-forming as the infernal flotsam moves. Now and again, a demonic face will form atop the sludge. Its agonized face gives a hint as to the sinister slime's origin.

Invisible Killer. The infernal flotsam's natural state is to be invisible to the naked eye. It slithers across the landscape, through a village, or within a cavern unseen, The only clue to the ooze's presence is the unholy stench its produces. By then, a victim's fate is already sealed. The slain creature is absorbed into the mass, torn to pieces and often ejected back out as an infernal jetsam. Too often, these shambling spawn are mistaken for the source of their sire's odor.

Rendered Down Hubris. Abyssal annals state that the infernal flotsam was once a devil count who sought a way to rob the Slime Lord of its alien intelligence and take direct command of the primordial horror. The count intended to unleash the Oozing Hunger and its spawn on the Abyss as a weapon of mass destruction. Not only would this tip the Blood War in the devils' favor, but would elevate the personal power of the fiend. Nothing went according to plan, as if often the case. Instead, the devil count found himself dissolved into unspeakable thing and spat out onto the mortal plane.

Driven mad by the experience, the former devil now plans to build its own legion of spawn out of the hapless creatures it encounters. Once its army is large enough, the infernal flotsam intends to find its way to the Abyss and usurp He Who Slithers.

Infernal Flotsam

Large ooze, Chaotic evil

Armor Class 7

Hit Points 262 (25d10 + 125)

Speed 30ft

Str 26 Dex 4 Con 20 Int 14 Wis 14 Cha 4

Saving Throws Str +13, Con +10

SkillsPerception +7

Damage Vulnerabilities cold

Damage Resistances poison

Damage Immunities acid, fire; bludgeoning, piercing, and slashing from nonmagical attacks

Condition Immunities blinded, charmed, deafened, exhaustion, poisoned, prone

Senses blindsight 60 ft., passive Perception 17

Languages -

Challenge 16 (15000 XP)

Absorb.

Whenever the infernal flotsam ends its movement on one or more other creature's corpses it absords and dissolves them. The infernal flotsam retains hit points equal to an absorbed creature's hit dice. The infernal flotsam may then use its spawn infernal jetsam ability as a bonus action.

Creatures destroyed via the infernal flotsam's Absorb ability can be restored to life only by means of a true resurrection or a wish spell.

Amorphous.

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

Legendary Resistance.(3/day)

If the ooze fails a saving throw, it can choose to succeed instead.

Siege Monster.

The infernal flotsam deals double damage to objects and structures.

Spider Climb.

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

Stench.

Any creature other than an ooze that starts its turn within 5 feet of the infernal flotsam must succeed on a DC 18 Constitution saving throw or be poisoned until the start of the creature's next turn. On a successful saving throw, the creature is immune to the stench of the infernal flotsam for 1 hour.

The infernal flotsam's stench can be smelled up to 30ft away, but is only dangerous within 5ft of the ooze.

Actions

Multiattack.

The infernal flotsam makes two pseudopod attacks as one action.

Pseudopod.

Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 15 (2d6 + 8) bludgeoning damage plus 7 (2d6) fire damage.

Superior Invisibility.

The ooze magically turns invisible until its concentration ends (as if concentrating on a spell). Any equipment the infernal flotsum wears or carries is invisible with it.

Spawn Infernal Jetsam.

The infernal flotsam spawns 1d4 infernal jetsams in any uncoccupoed square within 10f. Spawned infernal jetsam act immediately after the infernal flotsam on the same initiative count.

Legendary Actions

The infernal flotsam 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 monster regains spent legendary actions at the start of its turn.

Pseudopod (1 point).

The ooze makes a pseudopod attack.

Move (1 point).

The infernal flotsam makes moves up to its full speed.

Like Flies to Honey (2 points).

The infernal flotsam spawns 2d6 imps. The fiends appear in any unoccupied square within 60ft, are friendly to the ooze, and will fight to the death. The imps act on the same initiative count immediately after the infernal flotsam and any infernal jetsam. The ooze cannot use this legendary ability again if any summoned imps are alive. The imps return to the Abyss automatically when the infernal flotsam dies.