Ever wondered if using a bonus roll on a particular boss would actually grant you another chance at a mount or pet? Item and Rewards Designer Owen Landgren
took to Twitter to clarify where bonus rolls do and do not work for specific items.
I'll admit I was surprised to learn that the Garrosh weapons could not be won with a bonus roll. Blizzard's reasoning is they do not want you choosing between account-wide and character-level power when you bonus roll. Hopefully these clarifications will help you better spend your precious bonus rolls.