Though it's not a pure R/U Deck, I wanted to make one in honor of my favorite Ravnican guild: Izzet! But I wanted to try a different approach instead of normal goblin and spells combo.
THIS DECK HAS TO WIN EARLY (draw out a long game and this deck will lose quick).
By turn 4 your creatures should be able to deal A LOT of damage. If all goes well and you had a good hand you should be able to win within turn 10.
What you are trying to try to pump up Nivmagus and bioshift its counters onto Invisible Stalker for a hexproof tank. Hence this deck is filled with low costing spells; both as protection and as fodder for Nivmagus. Hence the land count is relatively low. Because we need to win early, an accumulation of more land after our key creatures are on the field is unnecessary.
So what your going to want to draw would be Nivmagus, Bioshift, Cackler, Stalker, and some low costing spells and of course the appropriate lands. From experience, if you draw a Nivmagus, Cackler, and Bioshift, assuming that your opponent doesn't make you discard them, the game turns out pretty well for you.
If you don't draw a creature on your first turn, I suggest you mull. This deck is heavily dependent on racking up creatures and swarming counters. It will be through creatures that we win so send those creatures out!