Giant Green Goop

Actions

Pseudopod. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 16 (3d6+5) bludgeoning damage plus 14 (4d6) acid damage and 4 (1d6) fire damage.  
Irradiate. (recharge 5-6) The Green Goop glows bright orange, heating any liquid it is in to searing temperatures. All creatures in the liquid with the goop within 25ft of it must pass a DC 17 Con check or take 4d6 fire damage. If the goop is not in liquid, the air around it is heated. All targets not submerged in liquid or behind cover within 50 ft of it must pass a DC 17 Con check or take 5d6 fire damage and 3d6 radiant damage. Ooze type creatures are not affected.

Reactions

Split. When a Giant Green Goop that is Medium or larger is subjected to lightning or slashing damage, it splits into four new Green Goops. Each new goop has hit points equal to one quarter the original goop's, rounded down. New goops are one size smaller than the original goop.

Legendary Actions

Giant Green Goop 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. Giant Green Goop regains spent legendary actions at the start of its turn.
Acid Splash. The goop casts acid splash.
Attack. The goop makes one pseudopod attack.
Move (Costs 2 Actions). The goop makes a full move action.

Lair Actions

On initiative count 20 (losing initiative ties), the Giant Green Goop can take a lair action to cause one of the following effects; it can't use the same effect two rounds in a row:
• The Giant Green Goop slimes a square area of ground it can see within the lair. The area is 5 feet on a side. The slime lasts for 1 hour or until it is burned away with fire. When the slime appears, each creature in that area must succeed on a DC 13 Strength saving throw or become restrained. When a creature enters the area for the first time on a turn or ends its turn there, that creature must make the same save. A restrained creature is stuck as long as it remains in the slimy area or until it breaks free. The restrained creature, or another creature that can reach it, can use its action to try to break free and must succeed on a DC 13 Strength check. If the slime is set on fire, it burns away after 1 round. Any creature that starts its turn in the burning slime takes 11 (3d6) fire damage.
• The Giant Green Goop slimes a square area of ground it can see within the lair. The area is 5 feet on a side. The slime lasts for 1 hour or until it is burned away with fire. When the slime appears, each creature on it must succeed on a DC 13 Dexterity saving throw or fall prone and slide 5 feet in a random direction determined by a d8 roll. When a creature enters the area for the first time on a turn or ends its turn there, that creature must make the same save. If the slime is set on fire, it burns away after 1 round. Any creature that starts its turn in the burning slime takes 11 (3d6) fire damage.
• The Giant Green Goop boils the acid sewage. Each creature within the lair must succeed on a DC 13 Constitution saving throw or take 7 (2d6) acid damage. Each creature within a body of acidic liquid takes an additional 1d6 fire damage.

A very potent ooze, infused with the foulest of taint, has made this section of sewer its lair. It seems to be some sort of hive mind of smaller oozes and occasionally splits apart and reforms. Its presence here is destroying the stone walls and will soon cause structural collapse.

Regional Effects

The region containing the Giant Green Goop's lair is warped by its magic, creating one or more of the following effects:
• Small bodies of water, such as ponds or wells, within the lair, turn highly acidic, corroding any object that touches them. Every time a creature starts its turn in a body of acidic liquid within the lair, it takes 11 (3d6) acid damage.
• Surfaces within the lair are frequently covered by a thin film of slime, which is slick and sticks to anything that touches it.

Prof. Bonus +4