Havoc Festival I would say is definitely a sideboard, and only side it in for control that you can't run over. Mainboard another Rakdos's Return and then put in 3 more Vexing Devil . Stromkirk Noble isn't as great as it used to be IMO becuase haste = everything right now. I would put in some Lightning Mauler too. Also 2 other good cards to put in depending is Foundry Street Denizen gets you in some quick hits on your turn 2. Also Burning-Tree Emissary let's you buff him by putting one out into another creature.