I was going through The Wanderer's Palace at some point last month without any problems until we came upon the Tonberry King. The boss fight revolves the concept that any adds that are killed will add damage to an attack executed by the Tonberry King.

We were trying to kill only a few adds so as not to overwhelm the tank and he became enraged that we weren't killing all of the adds. After he was killed, he complained that he carried us through the dungeon and said that he was going AFK and expecting us to leave. The rest of us sat around and talked about our lives and treated the dungeon like a chatroom; 20 minutes later, the tank came back and said, "you losers are still here?" and then rage quit as he should have in the first place. We got a replacement tank and finished the dungeon without a problem and without any penalty.