Ghostly Prison

Taxing combat instead of forbidding it is the design idea here, and the distinction is everything. A pure fog wall says "no"; this says "fine, but it costs you," and that conditional reshapes how the attacker budgets a turn rather than how the defender absorbs a punch. The math scales against width: one creature is a manageable tax, but a go-wide board pays per body, so an aggressor either commits everything (and drains its mana) or trickles in attackers at a rate the defender can answer. Crucially the tax is one-directional. It protects only its controller, leaving them free to swing back unimpeded, so it functions as a soft Propaganda-style lock rather than a symmetrical truce. The effect lives in the attack-declaration step, before blockers, before tricks: the attacker has to commit mana to even point creatures your way, which means the enchantment taxes intent, not damage. That timing is why it buys turns rather than preventing losses outright. Its weakness is the flip side of that targeting: a combo deck assembling its kill on the stack or a control deck closing with a noncreature win condition declares no attacker at all, and the enchantment goes blank, taxing nothing because there is nothing to tax. It is the white half of a small lineage of "make them pay to attack" pillowfort pieces, the answer to how a controlling deck survives aggression without holding up removal every turn, and a patient deck turns that purchased time into the win condition the enchantment itself never provides.