Electrodominance

The X in the damage clause and the X in the free-cast clause are the same X, and that shared variable is the entire mechanism. Most X-burn just scales up to kill something big; this one turns every point of that investment into permission to deploy a second spell without paying its mana cost. Pay ten mana and X is eight: you fire off eight damage while also unloading anything in your hand with mana value eight or less, its mana cost waived (though any required additional costs still have to be paid). The instant-speed clause is what turns the card strange, because it hands you a way to cast a sorcery on your opponent's end step or in response to a trigger, folding away the timing rules of whatever you tuck under it. That is the axis combo decks care about, and the reason the card became a fixture in suspend-payoff shells: spells with no mana cost, like Crashing Footfalls and Living End, have mana value zero, so an X=0 Electrodominance (the two red mana of ) puts them onto the stack at instant speed for free. What would normally sit in a suspend queue for turns arrives now, at a window it could never otherwise reach. The tension the card resolves is between two roles it can never fully commit to at once: a low X makes it a delivery mechanism for a free spell, while a high X makes it a burn payoff scaled to whatever expensive thing you want to chain into. The same number answers both questions, and you pick which half you are paying for.