Terentin finds herself in the unenviable position of having KO'd all of the geth within easy reach. And a squadful of more distal robots have turned to drawn beads on her. There's an upper limit to how many targets you can shoot with one pistol in an instant, as galling as it is to admit. So, step 1, she kneels behind some dubious cover, geth fire colliding with her shield.
The whites of her eyes are visible from orbit as they flick calculatingly from geth to geth. Step 2. The new omnitool whines warningly because about a dozen of its safety features, the ones kept intact for good reasons, fall to merciless task management. And then, reluctantly, vent power begins to build in places which it was not intended to collect.
The Commander swipes out jerkily at the air with the blade, in a pattern fed to her by a bent and inverted weather forecaster. Arcs of white electricity gain courage enough to flicker out over her sword-arm, forcing her active camouflage to flicker in concert. Parts of the Commander's body appear momentarily to be made only of lightning. Her omni spits out a tiny, smoking, unstable pellet of the same carbon-black steel as her sword, cometing past geth, shedding microflakes, dissipating.
Then there's a loud crack. It's very unlike the rumbling, distant thunder you get on Therum. A few geth explode as the rest in the path are washed out in an electrical storm. Garrus is perhaps uncomfortably close to its limit, and if he had hair it would stand on end.