And I Would've Gotten Away With It, Too

It may not be the most reliable, but it sure is fun to summon infinite Villains. The dream play is to have Recurring Villain and give him an Explorer's Hat, then trigger the Deathrattle to get another Recurring Villain in play with another Explorer's Hat in hand (I know the Deathrattle says, "resummon" but it will give you another body, at least in my experience). There's also Mok'Nathal Lion and Seeping Oozeling to copy the Villain's deathrattle to summon copies of themselves without a Hat.

If you're done trying to win and just want to do something stupid, I can think of nothing stupider than infinite Recurring Villains.