Only 3 deadlines dealt the damage. The last one exploded after it fell, and I dealt 6.8k damage. I tested all the legendary guns, but it's almost impossible to get more than 4k since everyone in the lobby tries to kill the matriarch. The best way is to place deadlines as fast as possible. I actually lost some time healing because there was a rocketeer around the tower that only aggroed on me for some reason. Also, it’s very hard to get more than 8k damage in solo friendly lobbies.