Overlord's Brand - Brands an enemy with the mark of Tyrannus, causing all damage dealt by the Branded foe to be mirrored to the caster's primary target, and all healing done by the Branded foe to be amplified and mirrored to the caster.
Sadly Affliction Warlocks and Shadow Priests alike REALLY hate this fight, they can not just stop damage on a dime say like a mage or rogue can. Healers have to be spamming heals on the tank when this happens.
Short answer: YES, that was the damage that the tank was referring to. Could you do anything about it: NO.
On the bright side the tank didn't sound like he did die so you did just fine and everyone did their job :)
