If your opponent controls a monster and you control no monsters: Special Summon 1 FIRE Beast, Beast-Warrior, or Winged Beast-Type monster from your Deck. Its effects are negated and it is destroyed during the End Phase. You can only activate 1 "Onslaught of the Fire Kings" per turn.
How to Get
Negates the effects of your Effect Monsters / Destroys your Monster Cards
Special Summons from your Deck
Of course, the best card in SD EX is SR.