The latest challenge event in Final Fantasy Record Keeper is called “Gunblade of the Sorceress.” It launched on November 18th and ends on November 28th.
The rewards for beating the challenge are being able to recruit Final Fantasy VIII antagonist Seifer, as well as Zell and Squall. You’ll also get their Memory Crystals to break their level caps. The event announcement also says to watch out for Squall’s Memory Crystal II in upcoming event dungeons to take his level cap even higher.
If you’ve already recruited any of these characters then you’ll get a Greater Growth Egg instead.