Diablo 3's Season 25 theme has been outlined as part of an early look at Patch 2.7.2 by
Blizzard and it introduces a pair of new socket-able items -- seven unique Soul Shards based on the Lords of Hell.
"With the upcoming 25th Anniversary of the Diablo Franchise, we wanted players to delve into the darker side of the Nephalem's past," writes Blizzard. "In Season 25, players can embrace evil by infusing themselves with the essences of the Lords of Hell."
And with that there will be one of 3 Prime Evil Soul Shards that can be equipped into Helms (a nice little nod to the ending of the first game) with one of 4 Lesser Evil Soul Shards able to be equipped on Weapons. Soul Shards will also be able to be upgraded with a Hellforge Ember, which is a new seasonal-exclusive consumable.
Blizzard notes that all of the above can drop anywhere but Soul Shards have a greater chance of dropping from Bossess -- which is another very nice old school Diablo touch. No word yet on what stats or buffs or passives the Soul Shards will bring, but Blizzard notes "players will inflict new forms of pain and suffering on the demons of Sanctuary". Adding that their true power might require a few upgrades to unlock.
Season 25 and Patch 2.7.2 also features a few balance changes to items and sets, with the Barbarian's Hammer of the Ancients getting a power boost via items in addition to the Witch Doctor's Spirit of Arachyr set and other legendary Witch Doctor items.
Head here for the full Patch 2.7.2 PTR Patch Notes which is set to go live this weekend for two weeks. Which means Season 25 should be kicking off later this month or in December.