Final Fantasy Brave Exvius is a mobile game released in 2016 (2015 in Japan) where players collect Final Fantasy characters by playing a simplified turn-based RPG. War of the Visions: Final Fantasy Brave Exvius is a different mobile game that spun off from Brave Exvius that released in 2020 (2019 in Japan) that plays closer to Final Fantasy Tactics, but also allows players to collect Final Fantasy characters. Recalling an ouroboros situation, the two games are now collaborating. War of the Visions: Final Fantasy Brave Exvius characters are now collectible in Final Fantasy Brave Exvius.
The event is happening now and along with the new units and summons, there are also new login bonuses and new daily summons rewards that will be available until May 25. The main rewards for participating in the event are King of Leonis Mont and Vinera Fennes from War of Visions, and the Vision Card, Proof of Resolution and Resolve. The steps to unlock these rewards are complicated outside the context of the game, and involve moving through a series of steps with Summon Coins and NV Exchange Tickets. Luckily, Square Enix has outlined the process in more detail on this website.
The Brave Exvius games are no stranger to collaborations with the larger Final Fantasy world. Just last month, Rinoa From Final Fantasy 8 was available as an unlockable summon, and War of the Visions collaborated with its inspiration, Final Fantasy Tactics back in 2020.
Read more on gamespot.com