Blizzard announced the end of the Diablo III season on his Twitter account dedicated to the series. We already know that it will take place on August 21, and the theme of the next, 27 season, will be the Angelic Crucibles.
Once discovered by the Nephalem, these celestial artifacts can be used to Sanctify any equipable Legendary. Sanctifying an item forges it to have perfect antiquity stats on all affixes, while maintaining its legendary power. Additionally, this process adds one of three new powers unique to each class.
As in the previous cases, Angel Crucibles and Sacred Items will be limited to seasonal characters only and cannot be transferred to other characters after the season ends.