Checks and Balances

Cast this spell only if there are three or more players in the game. Whenever a player casts a spell, each of that player's opponents may discard a card. If they do, counter that spell.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6omhh8gdyjpb1hdb7p2cdc.