Boas. O SKT aqui tem razao.
508.5 - If a creature is put onto the battlefield attacking, its controller chooses which defending player or which planeswalker a defending player controls it’s attacking as it enters the battlefield (unless the effect that put it onto the battlefield specifies what it’s attacking).
Such creatures are "attacking" but, for the purposes of trigger events and effects, they never "attacked."
Criaturas postas em jogo a atacar, estao a atacar, mas para trigger events, nunca sao consideradas como se tivessem atacado, logo triggers de "Whenever [cardname] attacks" nao disparam.
Cumps