After the Main Tank died, the other players had no way of escaping death. They could run out of the Instance Dungeon, but that would take too long. Other than Lu Li, who could go into Stealth, everyone else was just waiting to get killed by the Boss.
"Dammit, that scared me."
Azure Sea Breeze was still little scared even after getting revived. When he kicked a pile of bones, he didn't receive the Bone Armor like everyone else did. Instead, a pillar of fire appeared which shocked him into forgetting that he was kiting the Boss and also dealt significant damage to him. Poor Azure Sea Breeze was the reason they got wiped again.
This Boss really tested the ability of Defense professions.
However, after the group had been wiped three times, everyone basically understood what Rattlegore did. It only had two tricks – Rust and Bone Needle. The former was used against the Main Tank, which forced him to kite. The latter was for everyone, but it wasn't a problem with Bone Armor.