Fera, Dawn's Vengeance

Flash, Double strike
Whenever Fera enters or leaves the battlefield,
exile the top card of each player's library, then
you may cast any number of spells from among
those cards without paying their mana costs.
For each card you don't cast this way, Fera deals
each opponent 3 damage and you gain 3 life.
If this card leaves the battlefield, or is put into
your graveyard or exile from anywhere, exile
it with a binding counter on it instead.