Sorry, but I don't understand "Grieving for the master" (foundation):

E: Commit: If your opponent's next form this turn is an attack , it gets -4 damage. Only playable if you have more momentum than your opponent.

If my opponent attempt to play a Attack, I can reduce -4 damage if this enhance?

Thank!

when you use the ability during an enhance step it sets up the floating effect that will, if the next form that your opponent plays is an attack, reduce the played attack's damage by 4

so it will work on the attack after you play it, if you opponent plays an attack

Thanks!! I'm understand now!

I'm from Brazil, and here we have many questions about this game.