I have a serious one though.
Sometimes, I gain twice the amount of gold for beating an opponent in the arena, just like with elemental master - but I didn't have full HP left. Why is that?
Taking these from xeno's wiki article.
"However, if the deck is rank 4-9, bonus is doubled.
If the deck is rank 3, bonus is multiplied by 6.
If the deck is rank 2, bonus is multiplied by 8.
If the deck is rank 1, bonus is multiplied by 10."