when you do a side battle the winner comes into battle right? that's how i figured it out.
Only if the side battle started with an already blocking EC, and he ended up winning. So if I attack, and you block with Pharaoh, and I play Sword of the Lord to start a side battle between Pharaoh and my EC, if Pharaoh wins that battle, he returns to the main battle. If he is discarded during the side battle, I win the main battle (unless you can bring in another EC via UN, etc. or get rid fo my hero).