Plasma is good if you can time the throws around corners, but more like average.
And you need a good ball with distance from you also.
In RT, Plasma and grenades can be very effective. Though the sneak part of it will probably not come into play, you could try to stealth bomb people, perhaps place containers down place bombs in them then detonate or on dead bodies.
Though I believe you'd be mostly restricted to PVE Turn based.