I defeated a boss and a ??? teleporter appeared. I went in it & had to fight 6 'Super Rare Enemies'.
(And, of course, me being me; that's when my eyes acted up and started burning and itching (Docs don't know why it happens) so badly that I could not open them, and tears were literally making waterfalls down my face as I run in circles blindly to 'Face Annihalation!' spammed by the monsters )