Frenzy Rites of Mogg

As an additional cost to cast this spell, sacrifice X permanents and pay X life.
Frenzy Rites of Mogg deals X damage to each opponent.
Creatures you control get +X/+0, first strike and trample.
If Frenzy Rites of Mogg is cast from your graveyard, each opponent sacrifices X permanents
Flashback {2}{b}{r}{g}