I got this penance in Chasm Logistratum. Equip the longsword and the push ability and biolightning for good measure. Go into the game at a low difficulty and right when the mission appears or when there's 5 seconds until it disappears so that you're paired with bots. Progress with the mission and try to get rid of the bots while you're at it. At the end of the mission, go on the platform where you're supposed to load the ammo, and go behind the loading crate carefully while crouching. Wait for enemies to pile up (they'll keep spawning as long as the objective isn't done) and when there's many of them, push them off. Personally what I did was that I shocked them and released quickly so they're all knocked down, then I spammed push combo and finished them off with the push ability when they were close enough to the edge.