B: Black lets me play Demon of Dark Schemes (read: Demon of Dank Memes), which seems like a good soft sweep, threat, and energy generator. the 3BBB is slightly prohibitive in a 2- or 3-color deck. Aether Hub can help with that.
If you want to stay in UR for Whirler Virtuoso and Harnessed Lightning, then I'd recommend playing Panharmonicon. Whirler Virtuoso makes infinite Thopters and infinite energy with Panharmonicon + 2 Decoction Module or 2 Panharmonicon + Decoction Module. Dynavolt Tower might be another good outlet for energy or way to build up energy with the spells you're playing in UR.
Any of the combos work. The nice thing about b and c is that they make infinite Thopters and infinite energy! (4 energy produced per iteration, instead of 3). Also, they don't involve getting 3 copies of the same card in play (which has lower odds than finding 2 and 1 of something). Then of course you can win with something like Reckless Fireweaver or just combat damage step.
If you add Panharmonicon to your decklist, then you have many ways to "go off" and it should be easier.