Starting today, The X-Men Vs Apocalypse alliance event will begin at noon EDT. The details have been released regarding the rewards, boost list and essentials on the official D3 forums.
Namely, the essentials will be 4* Mockingbird, 3* Quicksilver and 2* Human Torch. The boost list looks largely unchanged, consisting entirely of mutants. The 3* alliance reward will be Gambit and the 4* alliance reward will be the newly released Jubilee.
The event itself seems unchanged from its previous iteration so any strategies that worked for you last time are sure to work once again. Check out the official post for more details on the event.