Counterspell

Cards that counter a spell on the stack, or an activated or triggered ability, stopping it before it resolves. Hard counters like Counterspell and Mana Drain stop anything; conditional counters like Mana Leak counter unless an extra cost is paid; narrow counters like Negate and Essence Scatter hit only noncreature or creature spells. Some come attached to a body or a payoff, like Mystic Snake's enter-the-battlefield counter or Swan Song leaving a 2/2 token, and free options like Force of Will and Fierce Guardianship pay an alternative cost. Stifle and Disallow extend the role to countering abilities, not just spells. This is purely stack-acting interaction; permanents already resolved on the battlefield are untouched, so destroy-and-exile effects and control-change theft belong to other effect groups.