Blizzard will reveal detailed patch notes for Diablo 4's upcoming season 15 at BlizzCon in September, marking a departure from their usual practice of providing advance details. The season will introduce new seasonal items, returning favorites, and adjustments to the Mythic Unique item system. New features include "Challenge Dungeons," which are boss encounters with customizable difficulty in the open world, and "Overland Ambushes," where players must react quickly to being hunted by a demon. Players can expect new items called "Soul Splinters" that enhance jewelry with damage buffs, and revamped Unique items from previous games, such as Leoric's Crown. The season will also see the return of the "Rebirth" system from Diablo 3 and changes to the Mythic Uniques, including the introduction of weaker, Unique versions of Iconic Mythics. A public test realm (PTR) for these features will be available from August 4 to August 11.