Help with finding an Ooze boss for a lvl 5 party

[Pefgis]

I am dm-ing for a four member party of lvl 5 players, specifically a moon druid, conquest paladin, war cleric, and conjuration wizard(He has boots of flying).( I am loosely adapting a one page dungeon adventure by Michael Prescott called Lantern of Wiv, if anyone is curious. He makes really interesting stuff.)

Anyway, the climax of the fight is a once human mage turned mindless ooze that they will find inside a magical floating laboratory/tomb. I am considering home brew for this, but am looking for ideas of existing ooze monsters with some spell casting or weird effects. The lead candidates I have found are the Yaga goo from the creature codex(which I have absolutely no experience using.
) and possibly the adult oblex, though the eating memory and impersonating stuff doesn't really apply to my intended monster, which I see as reactive, basically mindless, and magical but volatile. Any spells this mage has left are vestiges of a former life and muscle memory. Necrotic, acidic, or poisonous touch seem appropriate, and I'm not above first level spells like magic missile or some cantrips.


Monsters encountered earlier on the adventure that may potentially soften the party include a spectator guarding a rival wizard's tomb housing information and a mcguffin, floor tiles enchanted with the equivalent of the catapult spell serving as traps in the dungeon (Ala a Zelda game)a gargoyle or two, and a gibbering mouther, the test subjects of the failed immortality experiment that resulted in the wizard turning into a ooze monster. There will be opportunities for rests, but also a ticking clock, as there are potential victims to rescue, and the tower will disappear within twenty four hours. If they are on it when it does, they will be unstuck in time for a week, with the rest of time passing normally outside the tower.

Any ideas as what to use for this oozard boss? Anything the party can hit it with at their level and classes that might take me unawares? Any help would be appreciated. Thanks!

[RickAllison]

Elder or Adult Oblex from Tome of Foes could be straight ported, it even has spells.

[Pefgis]

I considered the adult oblex really carefully, as it's spells and most stats are pretty fine for what I had in my mind, but being mindless, and not a canon oblex, the impersonation and eating memories abilities aren't what I initially intended, though certainly not unworkable or wholly inappropriate. It also has way more intelligence than I envisioned, but I guess I role-play that as instinct or something.

[J-H]

Arcane Ooze?
There's one in MM3 from 3.5, or there's a version on dandwiki.

[Pefgis]

The Arcane ooze does look pretty interesting, but is weirdly more anti-magic and reactive than my purposes really require. It is on my short list of candidates though.

[Imbalance]

How did the wizard turn? It might be interesting if it isn't entirely aware that it became an ooze...until it splits. Then your party must contend with two amorphous casters or more. Increase hp and have it be hostile to even its own divided selves. Have one climb on the ceiling and blast down while another slinks under the party's feet, getting caught in each others' AOE spells while causing no shortage of mayhem and damage to your heroes.

[Pefgis]

The wizard turned from overuse of an artifact she didn't truly understand,touching it cures wounds but leaves sickly glistening white patches where once were scars or injuries or blemishes. Overuse and prolonged exposure to contamination with arcane power scources in the tower resulted inutation,which her deluded mind saw as perfection and a cheat from death. The ooze is not much concerned with splitting as it is maintaining the perfection of it's whole,all Interlopers are seen as contaminants to be disposed of...unless they were foolish enough to use the healing artifact on grievous wounds enough to resemble it. Then it may get jealous .

[Vogie]

Remember you can always refluff other monsters into oozes by dropping the speed down. Attacks can be refluffed as consume or pseudopod attacks, Ranged attacks are replaced by things like the Catapult spell. Things like the Swarm ability can be replaced with the Amorphous feature instead

I only have Volo's on me, so I flipped through and you could use:

Banderhobb
Korred
Swarm of Cranium Rats
Yuan-Ti Mind Whisperer or Pit Master


I also second the Oblex idea, as that's in MToF, if one of them is the right CR.

[Pefgis]

Re-skinning some appropriate monster with ooze qualities and abilities is not a bad idea. I will give it more thought. Thanks.

[Magicspook]

What's the CR of the gibbering mouther?

You could also grab a bunch of smaller oozes and stick them together as if they were a single large ooze. Roll all of their attacks on one turn as if it was one very large mother-ooze; there are only a couple of oozes on the outside of the mound that can be damaged, in the middle there is the core, which has the statblock of an NPC mage, and any subooze that falls to half health is separated from the main body and becomes independent.
However take care: the more sludge the players hack off the main nodule, the fewer attacks it gets, so the encounter might turn into a sort of imverse death spiral where the encounter becomes progressively more easy as time goes on.