When I placed down a cave illuminator for the first time, I crashed with a strange crash report shortly after. I reopened the world, quickly put the difficulty on peaceful and destroyed the illuminator - only to crash again once I put the difficulty back on Normal.
I created another world to test this more, suspecting that the Flare Lights that the illuminator places might cause the crash.
So I spawned a creeper, placed a bunch of Flare Lights using the illumination wand - and crashed again shortly after with the same report. It seems the pathfinding algorithm of mobs does not like the flares.
Here is the crash report: http://pastebin.com/dSK3kQrP

EDIT: Just now tested it with just Astral Sorcery installed - same crash: http://pastebin.com/hSwszNg4