RedHydra
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Having a hard time picturing it but I know that Intellect Devours if played right are amazing creatures. One of my GMs did an adventure with multiple separate rooms connected by fog doors where you needed to roll a DC 20 Will save or be sent to a random room within the dungeon that could each have their own puzzle / brain themed area. If you want a potential lasting effect on the party you could have the creature apply this template to one of your party members.
https://www.d20pfsrd.com/bestiary/monster-listings/templates/psychoplasmic- creature-cr-1/
Other than that the best way to make adventures is to make a bunch of rooms and fill them with monsters. Aberrations regardless of CR will pose a challenge to your party plus by the description you've given of the creature I would wager it would probably be an aberration too.
Hopefully you got some sort of an idea from my jumbled up mess
