If you have 9 mana and Jarraxxs in your hand when do you play him?
This is my train of thought when to play Lord of the Burning Legion:
A) winning but you want to win with style, (awww yeah)
B) Next turn your opponent can kill you but raising your life back up to 15 will save you in attempt for a one turn turn around
C) you have some board control victory is undefined and you need something to tip the victory in your favor
D) your opponent has nothing on the field and your both top decking and your around 10 health
E) Your gambling Warlock's big gamble at victory, all or nothing moment.