As mentioned above, Arkham is a great candidate for an 8-drop. They have great stall potential in Harley, Croc, and Freeze, but since 7-drop Joker is such a waste, they're not really stalling TOWARD anything unless then deck has 8-drops in it. As with most people, I choose to use The Demon as my 8 (though I still stand by my claim that I chose him before it was popular, indeed, before there was a single Arkham deck posted here! :)), with Apocalypse joining him until I get a second Demon. If you have Bane, Croc, Freeze, and Etrigan out on turn 8, and it's not a difficult thing to do, the game is pretty much yours.