A message from Bungie explains: “When signing in next Tuesday, Vault of Glass will offer a Master difficulty option to launch for you and your fireteam. While there is no minimum Power requirement to enter, enemies will be at 1350 Power, so you will want to earn some Pinnacle Power and raise your Artifact levels before attempting a run.
“First up, Master Vault of Glass unlocks the final Triumphs required for the Fatebreaker raid Seal and title. Once completed, players may equip their in-game title and purchase the Bungie Rewards pin if they so desire.
“Second, Master Vault of Glass will also introduce Timelost weapons to Destiny 2. Timelost weapons can be comparable to Adept weaponry from Grandmaster Nightfalls or Flawless Trials Passages, but offer an additional perk in columns three and four for slightly more customization.
“Complete Vault of Glass Challenges in the Master difficulty of the activity, and you will be rewarded. Each week will feature a specific Timelost weapon for you to hunt, rotating alongside the available challenge. Once you’ve earned a Timelost weapon, you may also purchase additional rolls from the chest at the end of the raid (on Master difficulty) using Spoils of Conquest.”