I'll admit we had a couple wipes on the transition from phase 2 to phase 3. The theory was when the older raiders (playing since vanilla) heard "Deep Breath" called on vent, they shuddered and instinctively ran for the sides, remembering all to well the chaos when learning how to raid on this encounter. This left some of the other raiders stranded wondering where the hell their healers ran off to.
Lava waves crashing from the sides with Sartharion are impressive but nothing matches the intensity of leaping lava and praying you don't feared get into Onyxia's cleave let alone her breath. And don't forget the whelps! For many of us, this was our first dragon kill nearly 5 years ago.
We tried to appease the gods of server and lag with a traditional gnome sacrifice. Unfortunately we did it after the battle. Lucky for us the gods seemed please by our small token effort by dropping only death knight pieces to a raid with no death knights.