Dragon of Fury is one of the strongest cards in the game-- and, it comes with Battle Ready! In the late game, when cards are sparse (unless your opponent or you is using lots of blue cards), chances are your opponent won't have any cards in play. During this time, if you draw a Dragon of Fury, your opponent probably won't have anything to defend with right away-- promising you at least 6 direct damage to your opponent. In the late game this can be the few points of damage you need to win the game.
Strong against: an empty field, low-ally count decks.
Weak against: ally-heavy decks, cards with the ability Ambush.