This encounter received a lot of different nicknames during development, such that I don’t recall what the last one I gave it happened to be. It might have been “The High Cost of Education” or some silly nonsense like that, but the basic premise had always been that an “open rift” formed in the library, whereas previously the characters had only had to deal with the smaller “spatial distortions.” Going along with the theme of planar breaches and invasions and whatnot, I batted around a lot of different ideas.

I originally intended for there to be a single large breach, which would serve as a “solo” monster for the party to engage, but when I settled down to design the encounter after putting it off for such a long time, it occurred to me that I would still want the fight balanced between different creature roles, and somewhere along the way, the idea of including the students as a feature (to be protected) meant I had to rethink some things.

The original solo breach became three standard ones (artillery role), I added in two “breach trolls” (brute role) to attack the students directly (who could be utilized to help close the planar breaches), and then, a great big wizard controller to harass the party and distract them while the artillery pounded the snot out of them. >:D