Displacement Wave

The X here is a dial that reaches in both directions: scale it low and you clear the small permanents while your bombs sit untouched above the cutoff, scale it high and you reset the entire board to hands at the cost of your own developed side. That symmetry is the whole negotiation. Most blue mass bounce of this size is one-sided in spirit because the caster chooses the timing, and the timing is everything: cast it when your opponent is overcommitted and you are holding back, and a single sorcery can erase two or three turns of development while leaving you whole. The mana value cutoff rather than a creature-only clause is what gives it teeth against artifacts, enchantments, and planeswalkers in the same breath, which is rare for an effect that doesn't destroy anything. Nothing dies, so it dodges indestructibility and recursion punishment alike; what it buys is a tempo swing, not card advantage, and against a developed board that distinction separates a genuine blowout from a temporary stall. It rewards a deck built to rebuild faster than its opponent, which is a different question from whether the wipe itself is good. Pricing the cleanup off X means it always costs exactly what you ask of it, and the discipline is in choosing the number that leaves your threats standing while their board goes home.