Schmetterer der Ahn-Saat

Eile (Diese Kreatur kann angreifen und {T}, sobald sie unter deine Kontrolle kommt.)
Du kannst den Schmetterer der Ahn-Saat erschöpfen, sowie er angreift. Wenn du dies tust, kann eine Kreatur deiner Wahl in diesem Zug nicht blocken. (Eine erschöpfte Kreatur enttappt nicht während deines nächsten Enttappsegments.)

Embestidor de la simiente Ahn

Prisa. (Esta criatura puede atacar y {T} tan pronto como entra bajo tu control.)
Puedes espolear al Embestidor de la simiente Ahn en cuanto ataque. Cuando lo hagas, la criatura objetivo no puede bloquear este turno. (Una criatura espoleada no se enderezará durante tu próximo paso de enderezar.)

Fracasseur de la moisson Ahn

Célérité (Cette créature peut attaquer et {T} dès le tour où elle arrive sous votre contrôle.)
Vous pouvez surmener le Fracasseur de la moisson Ahn au moment où il attaque. Quand vous faites ainsi, une créature ciblée ne peut pas bloquer ce tour-ci. (Une créature surmenée ne se dégage pas pendant votre prochaine étape de dégagement.)

Distruttore della Messe Ahn

Rapidità (Questa creatura può attaccare e {T} non appena entra sotto il tuo controllo.)
Puoi stremare il Distruttore della Messe Ahn mentre attacca. Quando lo fai, una creatura bersaglio non può bloccare in questo turno. (Una creatura stremata non STAPpa durante il tuo prossimo STAP.)

アン一門の壊し屋

速攻（このクリーチャーは、あなたのコントロール下になってすぐに攻撃したり{T}したりできる。）
アン一門の壊し屋が攻撃するに際し、これを督励してもよい。そうしたとき、クリーチャー１体を対象とする。このターン、それではブロックできない。（督励されたクリーチャーは、次のあなたのアンタップ・ステップにアンタップしない。）

Ahn-Crop Crasher

Haste (This creature can attack and {T} as soon as it comes under your control.)
You may exert this creature as it attacks. When you do, target creature can't block this turn. (An exerted creature won't untap during your next untap step.)

Foundations Jumpstart

Haste (This creature can attack and {T} as soon as it comes under your control.)
You may exert Ahn-Crop Crasher as it attacks. When you do, target creature can't block this turn. (An exerted creature won't untap during your next untap step.)

Amonkhet Remastered

Haste
You may exert Ahn-Crop Crasher as it attacks. When you do, target creature can't block this turn. (An exerted creature won't untap during your next untap step.)

"Hesitation breeds dissension. To be worthy of the next life, you must never look back."
—Anep, vizier of Hazoret

The List

Amonkhet

All cards in the Amonkhet set that let you exert a creature let you do so as you declare it as an attacking creature, as do some of the cards in the Hour of Devastation set. You can't do so later in combat, and creatures put onto the battlefield attacking can't be exerted. Any abilities that trigger on exerting an attacking creature will resolve before blockers are declared.

If a creature has a targeted triggered ability that triggers when you exert it, you can exert it even if there isn't a legal target for that triggered ability.

If an exerted creature is already untapped during your next untap step (most likely because it had vigilance or an effect untapped it), exert's effect preventing it from untapping expires without having done anything.

If you gain control of another player's creature until end of turn and exert it, it will untap during that player's untap step.

You can't exert a creature unless an effect allows you to do so. Similar effects that "tap and freeze" a creature (such as that of Decision Paralysis) don't exert that creature.