Don't forget to put the card name on the card.
Actually, you may want to drop the costs to 4/3 or 4/2 if you want to keep the stats, as the effect is rather situational, since most don't actually run dragons. Or, if you want to stick with 7/5 cost, make the stats are 6/6 for both. Pretty sure that attack niche has yet to be filled in
. Unupgraded at least.
Also, maybe call the ability "Slayer" or something to that effect. Maybe "Frenzy" considering the chance to die, which, in my opinion, would be better off expanding it to all creatures, but increasing the chance to die.