D&D General What weird CR8 (or greater monster) did the evil water elemental cultists set loose in the flooded lower levels of a desecrated temple?

[el-remmen]

Are there any fiendish creatures that are from a flooded level of the Abyss or the Hells? Not up on my D&D infernal bestiary.

 

[Incenjucar]

Vodyanoi could be terrifying. Aquatic umberhulks.

 

[TwoSix]

Hmm. Desecration of an agricultural deity by flooding and water conjures images of stagnant fields full of mud and rotting vegetation.

I'm thinking some kind of spawning nest of shambling mounds templated with an earth or mud element. Focus on engulfing and slow rot, bludgeoning and poison type damage with lots of slowing and difficult terrain. Have the entire lower section be overrun with slimy vines, that the mounds can animate to prevent the party from just rangeing down the relatively slow-moving monsters.

I'd make them resistant to most of the common elemental effects, but possibly vulnerable to necrotic to emphasize that while they're foul and corruptive, they aren't actually undead. Of course, introducing necrotic energy into the mix could cause other complications...

 

[el-remmen]

Hmm. Desecration of an agricultural deity by flooding and water conjures images of stagnant fields full of mud and rotting vegetation.

I'm thinking some kind of spawning nest of shambling mounds templated with an earth or mud element. Focus on engulfing and slow rot, bludgeoning and poison type damage with lots of slowing and difficult terrain. Have the entire lower section be overrun with slimy vines, that the mounds can animate to prevent the party from just rangeing down the relatively slow-moving monsters.

I'd make them resistant to most of the common elemental effects, but possibly vulnerable to necrotic to emphasize that while they're foul and corruptive, they aren't actually undead. Of course, introducing necrotic energy into the mix could cause other complications...

Ooh. I am liking this direction. Maybe fiendish shambling mounds (part of what makes "elemental evil" evil in my homebrew cosmology is the corruption of the elements - which is not mean to be good or evil - by fiendish energy of their planes and from whence the evil elemental princes spawned).

 

[el-remmen]

Vodyanoi could be terrifying. Aquatic umberhulks.

I was just making a list of classic/common monsters that I do not own minis of and umber hulks were at the top of the list. This might be a good occasion to buy and paint some in aquatic colors.

 

[TwoSix]

Ooh. I am liking this direction. Maybe fiendish shambling mounds (part of what makes "elemental evil" evil in my homebrew cosmology is the corruption of the elements - which is not mean to be good or evil - by fiendish energy of their planes and from whence the evil elemental princes spawned).

Fiendish shambling mounds that reproduce by inhaled spores causing mycomorphosis (like illithid ceremorphosis).

 

[James Gasik]

My vote (even though I'm not a fan of it's 5e art):

 

[Lakesidefantasy]

A memory-eating ooze seems more in line with the "Mud Sorcerer Cult" that loves all these ooze and slime and mud, worshiping a syncretic form of Ogremoche and Olhydra, that I have has another faction I am planning to introduce later.

The Elder Oblex is an "Invasion of the Bodysnatchers" kind of monster with a Challenge Rating of 10. It is found in Volo's Guide (the one in the Multiverse may be missing the Sulfurous Impersonation entry).

 

[Deset Gled]

The evil water elementalist cultists...

What is down there?

A water elemental, obviously.

"Greater", for CR8. Probably evil. Probably.

 

[Stormonu]

In a black whirlpool at the center of the bleak, churning waters of the flooded level is the Aboleth* Ghyrtnovan. The water cultists summoned him, seeking knowledge and power to defeat the Earth cultists. Though the water cultists were careful to bind it, Ghyrnovan proved too cunning. It overtook the minds of the cultists and transformed them into its skum servants. These servants still haunt the nearby waters, bringing new subjects to their master for conversion.

Chained as it is, Ghyrnovan endures his prison in pain, if not patience. It seeks someone powerful enough to break its bonds so that it can return to its basalt undersea caverns and green waters. Of course, it plans to take its new servants and knowledge is has gained back with it, as they will provide excellent minions in its moves against its brethren...

Ghyrnovan has accumilated quite an eclectic collection of strange items of mystical properties, including the fabled Urn of the Grain Maiden, which has the power to reverse the blight of crops and makes domesticated beasts swell in size and fertility. Also, it is known that the collected wisdom of the water cult, including the original ritual that opened the portal to bring forth Ghyrnovan. It is said that the portal can be refocused elsewhere - either to forgotten locations on the Mortal Plane or other world like (or unlike) the chaotic realm from where Ghyrnovan was snatched.

* You can used a "Reduced Threat Aboleth" from Yawning portal, slightly boosted, if a straight-up aboleth is too much.