Cosmic Crucible

Two engines stacked in one enchantment, and the ceiling comes from how they feed each other. The first main phase ritual hands you four mana of any colors before you have spent a card that turn, a Simic answer to the ramp permanents green has long owned (think of a Mirari's Wake or a doubling effect, except this pours raw mana rather than multiplying it). The second half is a permanent Mirari, stapled to the same body: one noncreature copy per turn, with new targets on offer. The floor of that clause is a doubled removal spell or a second draw effect; the ceiling is a copied storm payoff or a game-ending X spell cast off the four mana the same enchantment just produced. The reminder text spells out the reach of that copy: because a copy of a permanent spell becomes a token, the trigger doubles noncreature artifacts, enchantments, and planeswalkers just as readily as it doubles instants and sorceries, which widens the pool of spells worth building around. That self-contained loop, mana added at the top of the main phase feeding the copy in the cast window that follows, is what separates this from either effect printed alone: the ramp arrives before you commit a card, so the spell you copy is already partly paid for. The once-per-turn limit is the discipline that keeps it from spiraling into a chain: you get one copy, chosen when it matters most.