再来
インスタント
あなたの墓地からクリーチャー・カード１枚を対象とし、それを戦場に戻す。そうしたとき、あなたがコントロールしていないクリーチャー最大１体を対象とする。その前者のクリーチャーはその後者のクリーチャーと格闘を行う。（それぞれはもう一方に自身のパワーに等しい点数のダメージを与える。）
「なぜ心臓を貫いたと言い切れる？そもそも心臓がどこにあるか分かっているのか？」 ――インダサの密猟者、トゥルンダン
イラスト：
Ikoria: Lair of Behemoths#177アンコモン日本語適正
裁定
The reflexive triggered ability from Back for More is put onto the stack at the same time as any other triggered abilities caused by the creature entering the battlefield.
If the target creature is an illegal target when the reflexive triggered ability tries to resolve, the ability doesn't resolve. If the creature you put onto the battlefield is no longer on the battlefield or no longer a creature, the target creature won't deal or be dealt damage.
You don't choose a target creature you don't control at the time you cast Back for More. Rather, a "reflexive" ability triggers when you return the target creature card from your graveyard to the battlefield. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal. Notably, Back for More isn't a crime, but the reflexive triggered ability potentially is.