It's more or less regular damage. You can see that they use the Breach and Clear Artifact Mod to weaken the bosses. Fusion Rifles are generally strong with one of the trade-offs being that they can't crit. Breach and Clear though enables them to do a lot more damage, so Rapid Frames gain really high DPS. Aggressive Frames are a close second to this. You can also say that Breach and Clear makes a lot of bosses much easier, because it's like a permanent Tether if you regularly shoot the boss with Grenade Launcher (and Anarchy does that really well).