A new trailer for Diablo 3: Reaper of Souls focuses on the expansion pack's added features and updates.
The first part of the trailer covers the new gameplay of Adventure mode, where players must travel across the land hunting bounties. It also introduces the Nephalem Rifts, mini-dungeons where players must hold out long enough to spawn a massive boss.
The second half of the trailer discusses new gameplay improvements and systems. Reaper of Souls introduces clans to Diablo 3, and adds a new Artisan NPC to your town base: the Mystic, who can remove weapon enchantments and add others. Reaper of Souls also adds a cosmetic Transmogrification mode similar to that in World of Warcraft, so obtaining higher-quality gear doesn't mean sacrificing a character appearance that the player is fond of.
Expect to learn more about Diablo 3: Reaper of Souls tomorrow when BlizzCon 2013 kicks off in Anaheim, California.