Battleborn is part of the Humble 2K Bundle 2 and for $15 or more, you can score it plus the Battleborn Summer Skins Pack, 230 Battleborn Platinum, Duke Nukem Forever, The Line, Darkness II, Civilization 5, NB2K16 Mafia II, and Borderlands, the Pre-Sequel.
Check out the full line up on the Humble Bundle site.