I have absolutely no idea how this happened, but I know that fans of Fortnite are currently going crazy! Epic tweeted out that Fortnite and Marvel are having a limited edition mashup. Shortly after, The Russo Brothers tweeted out that Thanos is coming to Fortnite.
— Russo Brothers (@Russo_Brothers) May 7, 2018
We don’t have confirmation from Epic themselves, but another source says that this will be a special game mode that will include players battling to capture the Infinity Gauntlet. Whoever captures the gauntlet will turn into Thanos and have the full power of the Infinity Stones. We will definitely update tomorrow when this mashup goes live.
The Avengers crossover event is indeed an LTM mode called Infinity Gauntlet. The mode went live today and is a Solo mode where you battle over control of the Infinity Gauntlet. As Thanos, you have more health and shields, the ability to jump high into the air, and the power of the Power Stone to shoot lasers at your opponents. If you die, the Gauntlet can be controlled by another opponent. Full patch notes are here.