Diablo III: Reaper of Souls

Apprentice mode for low-level players to play along with high-ranked players. Items always drop equally among all players.

A mail system allows players to send materials, gold, and items to friends on their list. There's also a chance of gift spawns when certain items are picked up, which can be sent to friends.

The Nemesis system: when killed by a monster, there's a chance the creature will level up and become a nemesis. It'll open a portal, step through it, and hunt one of the friends on the killed player's friend list. When the friend kills the nemesis, a reward is provided to all players involved.