Dogs Unchained owners can mix 2 Dogs, entirely on the blockchain. Choose which of each dog's traits you'd like to keep and create a Superdog. While 2 Dogs enter the Boom Boom Room, one Superdog comes out, and the other is burned, decreasing supply forever.
During the Booming process, the owner also selects which traits they'd like to keep. This affects the rarity tables of every Dog as traits become more and more scarce.
Every time Dogs are Boomed, the resulting Superdog receives a "Level" trait equal to the highest Level of its parents plus one. This level is displayed on a badge at the top left of the Superdog.
Booming is performed in the Boom Boom Room on the DU Web App. You can access it here: Boom Boom Room