Grumpy Bomb combined with Demolition legendary is a nightmare for Barik, especially if he's with another front liner. That's because he likes to set himself up in one place, and you are forcing him out every 10 seconds.
If you see Terminus with Seris run for your life because that's a fight you cannot win the best strategy is to either lure seris away from terminus or kill her without terminus even knowing cause he'll try to block all your shots letting her escape