Not knowing the rules because it’s your first battle, is understandable. But that’s pretty rare at this point in the league. This was in a rank 7 battle. Any player who puts moderate to serious effort into the battles, would easily notice. And every player with a functioning brain will probably notice.
Assuming they can count to 2, of course.
I’m not saying this guy was definitely malicious, but he took advantage of a glitch. He could have just not used a 3rd shield to keep the game fair. Either way, I’m more just satisfied that I got off a win against someone using 3 shields. I don’t have an amazing record, and this is one of the highlights of my short battle league experience.