Summoned players will even stick around after the host dies, putting the defeated player into spectator mode, unlike Elden Ring's normal system that returns them home. If the beta is a success, this essentially means that PC players can start and play through the entirety of Elden Ring with up to three friends in a shared game world.
The mod also takes into account other limitations of normal Elden Ring multiplayer by allowing mounts to be summoned by all players, and "friendly fire" can even be activated by turning on a PvP mode. Item drops from bosses will be applied to all players, progress is shared, and more.
That seems kind of neat! I've been playing Elden Ring entirely offline due to the way the ultrawidescreen mod works, but it sounds like this might work with it since it's not connecting to Elden Ring's servers themselves. Of course with anti-cheat turned off you'll probably want to make sure you know whoever you're connecting with intimately because I'm sure they could screw up your game save if they wanted.