This season, all Fortnite battle pass owners can access Deadpool's weekly challenges to unlock the Marvel superhero skin. Once again, you have to start the week by finding a special item, affiliated to Deapool's universe. This time, it's a black marker that you'll have to find. Start by venturing into the hero's secret room, then turn on his computer.
Then return to the main lobby of the battle pass. Go to the "Agents" tab, then click on Brutus' portrait. The marker is on the colossus' desk, prominently displayed.
All you have to do is click on it to complete the challenge and move on to the next one! Finally, note that Deadpool's challenges are strictly sequential: you must complete them in the right order, according to their release date each week.
