How to buy Back 4 Blood items ?

Back 4 Blood is a thrilling cooperative first-person shooter game. Play with up to 3 of your friends online or go solo and lead your team in battle. Choose from 8 customizable Cleaners, one of the immune survivors, and a range of lethal weapons and items. A new "rogue-lite" Card System creates different experiences each and every time, putting you in control to craft custom decks, roll different builds and undertake more demanding fights. You are at the center of a war against the Ridden. These once-human hosts of a deadly parasite have turned into terrifying creatures bent on devouring what remains of civilization. With humanity's extinction on the line, it's up to you and your friends to take the fight to the enemy, eradicate the Ridden, and reclaim the world.