門の魔道士
クリーチャー — 人間・ウィザード
瞬速
門の魔道士が攻撃クリーチャー指定ステップ中に戦場に出たとき、攻撃クリーチャー１体を対象とする。あなたはそれが攻撃するプレイヤーやプレインズウォーカーを選び直してもよい。（それはそれのコントローラーやそれのコントローラーのプレインズウォーカーを攻撃することはできない。）
イラスト：
Commander 2017#13レア日本語適正
裁定
You may cast Portal Mage outside of a declare attackers step. If Portal Mage enters the battlefield outside of a declare attackers step, its ability simply doesn’t trigger.
Reselecting which player or planeswalker a creature is attacking ignores all requirements, restrictions, and costs associated with attacking.
Reselecting which player or planeswalker a creature is attacking doesn’t cause “whenever this creature attacks” abilities to trigger. Notably, the Curses in this set (such as Curse of Vitality) won’t trigger while Portal Mage’s ability is resolving.
If you reselect which player or planeswalker an attacking creature is attacking, that creature is still considered to have attacked the player or planeswalker as declared, but it is now attacking the new player or planeswalker.
If an ability targets something controlled by the “defending player” of an attacking creature and the defending player for that creature changes before that ability resolves, the ability won’t resolve because its target has become illegal.