Blessed Bagpipes

When you declare Beast as a challenger, both his triggered ability and Blessed Bagpipes’ triggered ability go into the bag. The active player chooses and resolves their triggered abilities first, so you resolve Beast’s ability and gain 1 lore while your opponent loses 1 lore, bringing their lore total to 18. With no more triggered abilities in the bag for you to resolve, your opponent then resolves the Bagpipes’ ability and gains 1 lore, which brings them back up to 19. This all happens before damage is dealt.