While full details have still yet to be revealed, it will apparently "include a little bit of everything," including campaign content, co-op mission, exploration in War Zone and Drop Zones and more.
The pre-order beta begins on Xbox One on August 14th (a week later than PS4), while the open beta commences on August 21st for all players. We haven't got any times yet, but Crystal Dynamics will be hosting a second Marvel's Avengers War Table livestream on July 29 at 10AM PT / 6pm BST with more information.
Looking forward to this? Let us know if you'll be trying the Marvel's Avengers beta in the comments.