为 心之所纵 寻找最佳的先驱套牌，包括其胜率、热度，以及该牌在万智牌：竞技场中的合法赛制！
Whenever an opponent casts their first spell each turn, that player exiles the top card of their library. If it's a nonland card, you may cast it without paying its mana cost.
