According to the patch notes wording. I’d say that you should get the rewards even if you lose the battle. Unless you retreat.
Now if this is recent. Please check your battle log. Find the player, look at their defense and see if they themselves have a Gnome on defense.
You will only get rewards if the AI replaces a normal troop with a Gnome. No rewards if the Gnome is put on Defense by another player.
1 Like