Phantasmal Sphere

A self-built timer with a sting in the tail. The upkeep trigger grows the body by a counter every turn, but the tax compounds: keeping it alive costs one mana per counter, so the longer it lives, the harder it pulls on your mana, until the math tips and you let it go. That escalating cost is the discipline balancing a flier that would otherwise run away with the game on its own. The genuinely strange clause is the leaves-the-battlefield trigger: when it finally dies, gets bounced, or you stop paying the tax, the opponent gets an X/X flier sized to exactly how big it had grown. That inverts the usual upkeep-creature logic, where releasing the creature is a clean exit. Here, the aggressive line (riding it large and dropping it late) hands across the biggest gift, while bailing early concedes the least. Every turn you keep it, you are weighing tempo now against a delayed liability you are actively building for your opponent, a calculus most Illusions of the era never demanded; their drawbacks ran to flat mana upkeep, not a payoff that scaled into enemy hands. The design is probing how much downside a growing threat could carry before its controller stopped wanting it on the table, and the answer it settles on is uncomfortable by intent.