You have to function like clockwork otherwise everything falls apart. During DPS prep both players killing the mobs must stay alive. If one of them dies it's 90% game over as the other person will quickly become overwhelmed, needs to leave their position to res which will cause even more chaos. Most mobs and all orange bars spawn on the stairs. If your titans can pretty much instakill them, then you're golden as the few red bars that spawn near the bottom are manageable. But god forbid a wave breaks through. Then you're toast. During DPS you also need a bit of luck as I've seen the Knight simply walk away.