Seasons will be a new game mode in 2.1. They will be running in parallel to the current Normal and Hardcore, giving you a total of 4 modes to choose from: Normal Non-Season, Normal Season, Hardcore Non-Season, and Hardcore Seaon.
Seasons have a limited duration and players participating in them will start from scratch in each season. During a season, players will start completely new characters and compete with others for the top of the Leaderboards.
Season mode can be selected when creating a new character, similar to Hardcore mode now.
Existing characters will not be able to compete in Seasons.
When choosing to create a Seasonal character, you will be off to a completely fresh start: No gold, no Paragon Levels, empty stash and no (levelled) artisans.
You will also be unable to play with any non-Seasonal characters.
The separation is comparable to that between Hardcore and Softcore right now.
Seasonal characters will take up one of the regular 12 or 15 character slots and will remain in this slot after the end of a season, simply having their Season status removed.
Progress in Seasons is measured by your position on the new Greater Rifts, Seasonal Achievement, and Conquest Leaderboards.
Conquests are new, special Achievements exclusive to Seasons and the fastest players to get them will be featured on the Leaderboards.
Possible Conquests include reaching level 70, clearing each Act in under one hour, killing Malthael and the Soul of Evil on max level and T6, and reaching Tiered Rift level 30.
Each Conquest exists twice: Once for Normal and once for Hardcore mode.
The first season will start on Friday, August 29th. Check the exact time for your region here.
The duration of seasons has not yet been determined, but expect a duration of about 2-3 months.
Later seasons might also change some rules of the game around, but the first few will most likely be vanilla.
When a season ends, all your progress will roll over to the non-Seasoned game mode.
This includes items, Paragon Experience, Gold and so forth.
There will be a new interface to transfer items over to the regular game mode.
Seasons will feature exclusive Legendary items.
These items will only be acquireable in the non-Seasoned game after the end of the season they started appearing in.
Additionally, Seasons will reward you with exclusive Transmogrifications and Banner styles.