プーカのいたずら

01/05/2008

Even if you don't plan on exchanging control of any permanents, if you can choose two legal targets when the ability triggers, you must do so. If you can't, then you don't choose any targets.

01/05/2008

能力が解決する時点までに、いずれか一方の対象が不正な対象になった（戦場を離れたか、その他の理由によって）なら、交換は起こらない。両方の対象が不正な対象になったなら、その能力は解決されない。

01/05/2008

You choose two targets such that as a set, all of the targeting conditions are met. That means, for example, that if you control a nonland permanent whose mana value is lower than any of your opponents' nonland permanents, you can't choose it as a target. (If you did, you'd be unable to choose a second target.)