Dough is resting, all ingredients are chopped and diced. But I don’t have enough Mozzarella. So I’m adding a little cheddar, and I have about a cup and a half of Caesar Blend Cheese. (Asiago, Parmesan & Romano).
Will my pizza be awful or awesome if I mix it in?
No expert here but since you need answer fast…my redneck opinion is that the mix is more pizza appropriate than the cheddar…for that matter unless you know you like cheddar on a pizza I’d leave the cheddar off (I love cheddar but IMO its not really a pizza cheese).
I’m not fond of cheddar on pizza either, and would prefer not to use it if I don’t have to. 
And the answer is: Awesome! I will do this again on purpose.
The local Papa Murphy’s uses just a smidge of cheddar, mixed with mozz, as a final sprinkle over the toppings, so a little bit of cheddar is okay, but you definitely don’t want a big ol’ glob of it.
A variety of cheeses is a must on a pizza! Mozzarella by itself is pretty flavorless, and texture-wise it just gets soupy. My favorite pizza blend is mozzarella, parmesan, asiago, romano, and provolone.