[Omen] troops that explode a gem on defense are crediting the offensive player with subsequent matches.
Set up defending team with [Omen] traits
Offensive player starts the game
Gem explodes per the trait; credits defending team with mana as expected (sometimes credits, known bug apparently)
Any resulting matches AFTER the explosion credit the OFFENSIVE player - including skull matches
This makes using these troops on defense utterly stupid as it yields an advantage to the other team.