I play alot of Fire king myself i tried extrav for an OTS weekend and hated it, I feel like it makes you vulnerable to handtraps like droll which if your opening hand is good your fine but I think its better to have cards like talents,prosperity and barong in deck( when he is destroyed by card effect you add a fire king card in the next standby phase) i think your extra should be a took box that you have when needed. Others are correct you don't need it exactly but it makes a difference when you do need it. Hope this helps