Generator Rex: Agent of Providence

Omega Builds is the power you can use once you've gotten enough Nanites. To see how much Nanites you got, check the blue bar in the top left corner.

Every time you collect Nanites and score a good combo (up to 10 or more) your Nanite bar will fill almost fully. To use it, press RB and your character will start using an attack that's devastating to enemies. It will slice and dice itself, you just need to control the direction of it. It will most likely pop during your first playthrough. If you want this faster, then kill loads of enemies, and when they stop spawning, reload the checkpoint and re-do what you just did.