I had this pretty cool dream last night that I was a wizard, and this powerful hellish creature from another plane of existence came into our world to kill me. I sent dozens of monstrous allies to wear it down and so I could keep my distance while I prepared my final spell (we were all flying around as this was happening). Finally when the fiend defeated my last ally I cast my banishment spell and the thing returned to whatever dark place from which it sprung.
So let that be a warning to the rest of you.