I think Regan is going as Johnny's plus one? I have to work that out with Jay. Would be interesting if Regan saw Crystal and Johnny flirting, but if she's going with Kurt then I don't know what will happen.
Regan's illusions are very realistic. She could fool Crystal into using her powers and hurting people? Or maybe just attacking Regan? Or she could make it so that Crystal doesn't recognize Johnny (or vice versa) and see how that all plays out. Because Crystal and Johnny are about to get nakey, right? That would be a blow to his ego if she didn't recognize him....