My group saw this monster behind the wall of force as it leapt up to attack them but was foiled by the wall. Our mutant sorceress, Charisma, goes progressively more green in the presence of radiation so her hair turned green and animated. The party completely avoided the beast (though the fighter wanted to try and kill it “for treasure”).
Armour Class 10
Hit Points 350 (21d20+147)
Speed 40 ft., climb 40 ft.
STR 30 (+10) DEX 11 (+0) CON 24 (+7)
INT 1 (-5) WIS 8 (-2) CHA 1 (-5)
Damage Immunities acid, lightning, bludgeoning and piercing
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Damage Resistance cold
Senses blindsight 60ft. (blind beyond this radius), passive Perception 8
Challenge 15 (13,000 XP)
Amorphous. The ooze can move through a space as narrow as 1 inch wide without squeezing.
Spider Climb. The ooze can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Magnetic Pulse. A plasma ooze is surrounded by an aura of magnetism that allows it to attract metallic objects and creatures. At the start of the ooze’s turn as a bonus action, the ooze makes a contested Strength check against all metallic creatures, all creatures wearing metal armor, and all creatures wielding metal weapons within 30 feet. If it beats the check of a metal or armored creature, that creature is pulled 10 feet closer to the ooze and cannot move away from the ooze for 1 round. If this causes the creature to move into a square occupied by the plasma ooze, the ooze can attempt to engulf that creature as a free action. If it beats the check of a creature wielding a metal weapon, that weapon is disarmed and pulled 10 feet closer to the ooze. Unattended metal objects of size Large or smaller are automatically pulled toward a plasma ooze. Unattended metal objects automatically take engulf damage (DMG pg. 246. Magic items are assumed to have resistance to all damage types). This magnetism is supernatural in nature and affects all metal objects.
Pseudopod. Melee Weapon Attack: +15 to hit, reach 20 ft., one target.
Hit: 22 (4d6 + 10) bludgeoning damage plus 18 (4d8) lightening and 18 (4d8) fire damage, and the target is grappled (escape DC 18). Until this grapple ends, the target is restrained, and automatically takes pseudopod damage at the start of its turn. The ooze can’t constrict another target however it may continue to make pseudopod attacks.
Plasma Rays (On a natural 18+). In addition to its pseudopod attack it shoots 1d4 rays at random (separate) targets. No more than one ray per target.
Plasma Ray. Range Natural Weapon Attack: +5 to hit, range 60 ft., one target
Hit: 18 (4d8) lightening and 18 (4d8) fire damage
Engulf. The ooze moves up to its speed. While doing so, it can enter a Gargantuan or smaller creatures’ spaces. Whenever the ooze enters a creature’s space, the creature must make a DC 18 Dexterity saving throw.
On a successful save, the creature can choose to be pushed 5 feet back or to the side of the ooze. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.
On a failed save, the ooze enters the creature’s space, and the creature takes 10 (3d6) lightening/fire damage and is engulfed. The engulfed creature can’t breathe, is restrained, and takes 21 (6d6) lightening damage and 21 (6d6) fire damage at the start of each of the ooze’s turns. When the ooze moves, the engulfed creature moves with it.
An engulfed creature can try to escape by taking an action to make a DC 18 Strength check. On a success, the creature escapes and enters a space of its choice within 5 feet of the ooze.
Split. When a pudding that is Medium or larger is subjected to sonic or slashing damage, it splits into two new oozes if it has at least 50 hit points. Each new ooze has hit point’s equal to half the original ooze, rounded down. New puddings are one size smaller than the original pudding.
This amorphous blob of violet energy ripples like a globe of floating liquid. It periodically lashes out with tendrils of blue light.