It seems very fitting that the first monster here is one related to education. Isaac’s campaign has a bit of a school setting, and this here is one of the bigger monsters being featured.
It is strict and authoritarian, lives in the school office, and eats students every once in a while. It can feel creatures coming by their footsteps, and can psychically assign detention to those near. Sounds like a high school nightmare to me!
Creating this monster was basically an exercise in beefing up a Gelatinous Cube and fitting in some flavor (like tremorsense and telepathy). In the end we get a CR 15 ooze!