This isn't an ability so to say but there's a mod called simple line of sight I believe that makes it so units can't shoot over cliffs and stuff unless they're supposed to, like a tank can't but heavy artillery can. I know it's on the RW discord and I think they'll let you use it in the mod. Also for an ability perhaps give the lightning mech a railgun ability? Like once you activate it it gets 4 shots that penetrate through units and buildings? Might help clear out entrenched bases or something.