Lilting Refrain

Counterspells normally trade their power for the moment they cost their mana; this one inverts the relationship by rewarding you for dropping it early and letting it sit. Each of your upkeeps the tax can climb, and the enchantment becomes a slow-burning threat an opponent has to play around without knowing when it will fire. A play that does nothing visible accrues into a Mana Leak, then a near-hard counter, then a wall no real spell pays through, and because the denial lives on a sacrifice ability, you can fire it at instant speed in response to any spell on the stack. The cost is information and tempo: the card sits face-up, telegraphing a counter that only grows, which lets a careful opponent bait it on something cheap before committing to the spell they actually need to resolve. Tying its strength to elapsed time rather than mana invested up front makes it a control piece that wants the game to go long and punishes anyone who lets it. The single sacrifice is the constraint that pays for all that accumulated power: every upkeep of stacking verse counters buys exactly one answer, so the threat is in the holding, not the spending. As design it captures a specific blue idea, not the wall of denial but the lingering threat of denial, an enchantment that taxes every future play simply by existing on the battlefield.