krenko and hellrider
I don't think Fervor is worth it. You're casting lots of your guys on 3 mana anyways.
WIth a deck like this you could consider Hellion Crucible in place of some lands.
And I would recommend Rummaging Goblin to help get good things in your hand. It doesn't actually draw you cards, but it is a goblin on the table to power-up Krenko and block if need be, and whenever you draw land or other unnecessary things late game you can pitch them.
I really like Arms Dealer in this deck, and if there is every room in the mainboard, he seems like a great fit.