Relentless Assault
The original extra-combat spell, and the template every successor has been priced against. Its design idea is brutally simple: pay to fold a second attack step into the same turn, untapping the creatures that already swung so they can swing again. That untap clause carries the weight. Without it, the extra combat would only matter for creatures held back; with it, the spell doubles the damage output of a board already in play, so it closes games rather than buying tempo. The price keeps the effect disciplined: four mana spent on the swing leaves nothing back to protect the attackers, so the spell rewards a board that is already winning and punishes a stalled one. Every later take on the shape iterates on that statement: Aggravated Assault added a repeatable mana-sink loop, Seize the Day attached a flashback, Waves of Aggression and World at War layered rebound and rider conditions on top. Each variant adjusts the rate by bolting on a restriction or an engine, but all of them trace back to this clean four-mana version of the idea. It defines a category rather than dominating one: not the most efficient extra-combat enabler ever printed, but the baseline against which the efficiency of every other one is measured.
