Whenever Cheering Fanatic attacks, choose a card name. Spells with the chosen name cost {1} less to cast this turn.
Effects that reduce the generic mana cost of a spell can’t reduce that spell’s colored mana requirements.
You don’t need to choose the name of a card anyone intends to cast this turn. You also don’t need to choose the name of a card that can have its cost reduced. For example, some Cheering Fanatics are enthusiastic about Shock or Mountain.