Just for clear up. I cant havr {Origin spellbomb} in a mono {U} deck right?
Correct, it can't have an outside mana cost in its effect at all. Flashback is the same way; a {Forbidden Alchemy} also could not go in a mono {U} commander deck. Of course, house rules can be made, and are encouraged, but in the official rules they have to be strictly within your commander colors.
Thanks! It'd have been awesome in the {Arcum Dagsson} deck im making
{Thopter Assembly} and {Thopter Squadron} could make you plenty of artifacts to sac. And come on, they're Thopters!