Festival

A one-mana white instant whose only job is to switch off combat for a turn, and one whose timing restriction is the entire design. It can only be cast during an opponent's upkeep, which means it is not a defensive trick you hold up against an incoming swing; it is a pre-emptive declaration made before the turn's plans have been laid. You spend the white mana, on their clock, betting that the attack you are denying is worth more than the mana and the card. That structure makes it closer to a Fog with a worse window than to a true combat answer: a real Fog responds to declared attackers at instant speed, while this one commits in the upkeep step, after the opponent has untapped but before they have drawn, played a land, or developed anything that might change whether the swing even happens. The reward for accepting that friction is symmetry-breaking on a stalled board: a defensive deck with no interest in attacking can blank an opponent's alpha strike for a single white. The card dates to a stretch of design where Wizards was still testing how upkeep-locked timing could price an effect down, before the Fog-style template settled into the cleaner instant-speed window that left this one behind.