This would make more sense for mayhem. Mayhem is a novelty because it is fun, but yet it changes modes. Full power can refer to supers and heavy ammo. Making a master proud would be to show off your training from your master, AKA your light powers such as supers. The Gjallarhorn quote refers to a rocket, or heavy ammo, and destruction within the quote is the whole theme of mayhem. I don't like Salvage as an answer because it doesn't make as much sense. A new day is upon us can refer to mayhem being a new type of crucible in the taken king. Also, showing difference to brothers is showing the differences between the classes. Showing no mercy is unleashing your full power, AKA abilities. Carrying a great power which leads to victory is holding heavy ammo or being super-charged. A lavage is a washing out with medicine, so you could be cleansing the battlefield of enemies with a taste of their own medicine, supers.