Brave-Eyes Pendulum Dragon's effect is activated on the window where the materials are gone already, but Brave-Eyes itself is not on the field yet. Even though the wording on the card clearly says its effect activates after it is summoned, meaning after it hits the field.
This "cheating" prevents Aster from activating D-Hero Dystopia's effect, since there's nothing to target on Yuya's field when Dystopia's ATK is reduced by Brave-Eyes' effect.
But don't blame the character, blame the anime duel writer for this asspull.
This actually isn't the first time such "cheat" happened, it already happened once in Yu-Gi-Oh! R manga.
Yami Yugi was able to summon Vandalgyon because he destroyed Tualatin with Vandalgyon's effect, before Vandalgyon hits the field. Even though the effect should have activated only after Vandalgyon hits the field.
Anoymous
