Apologies first off for the vagueness of this question but it's been a couple days since the game where this happened and I forget the full details.
We had a 4 player game, and I had three heroes and one ally. An enemy engaged me and I defended with the ally. The shadow effect revealed dealt damage to the ally and killed it. Is the attack still considered defended at that point? I want to think yes because I assigned a defender prior to that point but it was a question we couldn't find covered in the rules.