https://www.polygon.com/fortnite/2018/5/7/17326616/fortnite-battle-royale-avengers-infinity-war-event-date-time

A limited-time event begins in Fortnite Battle Royale tomorrow, May 8, which will bring a huge Marvel Universe character into the game. Thanos of Avengers: Infinity War will star in a special crossover mode in Fortnite Battle Royale: Infinity Gauntlet Limited Time Mashup.

The Avengers: Infinity War-themed mode shakes up the standard Battle Royale formula, according to Entertainment Weekly, which has details on the campaign. Players can find the Infinity Gauntlet on the map, and whoever grabs it can equip it and actually become Thanos in-game.