I got this challenge like 15-20 pvp games after I started trying for it, and it was frustrating as heck. So stay awhile, and listen:
• Take Weighed Down and Stick n’ Sap. If you’re specifically trying to grind out for the OM kills, this is the most grenade damage you’re gonna get. It takes some practice to land so if you’re not confident with landing the grenade, still practice with Triple Threat, but that combo is the best 1v1 helix WF gets.
• Try to see if you can fight him alone at level 1. This works most often in Meldown, sometimes in Incursion, don’t play WF in Control. With Weighed Down, you can reduce OM’s dps to the point where you’ll beat him easily through his grenade as long as you’re landing shots. Not a guaranteed kill by any means though, especially not without a helpful teammate or good aiming at his cloak.
• Don’t forget ult. A grenade and like 50 ult bullets is a dead OM, and it works right quick.
• Prey on bad OMs. I feel bad about this one, but like 6 of my kills were just on one OM in Incursion who kept trying to backdoor our sentry, and I was always on the prowl for him and immediately rushed in for the kill once I saw him on my map. If an OM throws himself out of position, be the first to react.
• Avoid good OMs without teammates. His grenade will outdamage yours, his rifle is more reliable to aim, and he has napalm at 2. If their OM is good (especially if he uses his teammates well) just leave it be. Trying to kill him without your team will prove to be infuriating.
• Swiss Cheese reveals his cloak.
• Go in with a friend or premade. I unfortunately didn’t think of this while I was doing it, but having a Ghalt or a Kelvin that you’re communicating with will make this challenge so much easier.
• Unless you find overwhelming success on one game mode or you find one not fun, alternate between Meldown and Incursion now and again, or even just the maps on each mode if you can. The change of scenery can be surprisingly helpful and refreshing.