Seasons – special quest runs that are separate from the regular Diablo 3 RoS game. You start with a new player with separate stash, gold and Paragon levels. Seasons run for a limited time and participants get first dibs on Seasonal Legendary Items that drop only in the Season. Once the Season ends, the Seasonal Legendary Items are moved to the regular loot table for all players. Patch notes say that the first Season starts on Friday.

Greater Rifts – infinitely-scaling Nepahelm rifts that get harder with each time you finish the Rift within 15 minutes. You get a chance to go to the next level or upgrade a Legendary gem for several ranks from the NPC that appears.

Conquests – Seasonal Leaderboards that immortalize the first 1000 players to finish the Season and achieve certain trophies.

Seasonal Item Set – every Season, Diablo 3 RoS gives participants a piece of the current Seasonal Item Set. If you participate in each Season, you get the set sooner than others. It looks a bit frightening though–great for Witch Doctors!

Legendary Gems – since Nevalistis said that you can upgrade a Legendary Gem in the Greater Rift, I’m assuming that these problematic babies have been ironed out and are implemented properly in Patch 2.1.0.

For more details, you can visit the official site. Of course,  this site is the perfect place for you to buy Diablo 3 items.