Bethesda's latest Fallout 76 blog is a deep dive into Vault 94 (opens in new tab), the location of its first four-player raid. While the blog notes this raid can be attempted solo, " a full team of level 50+ characters" is recommended.
Vault 94 was filled with pacifist gardeners who were given the job of restoring the Wasteland after the bombs and armed primarily with packets of seeds. The now empty vault has since been taken over by nature, which would sound like a recipe for vine monsters if Vault 22 in New Vegas hadn't done that already.
Fallout 76's new instancing will be used for the first time in this raid, insuring that teams aren't interrupted by other players (and that more powerful players advancing ahead of you don't raise the local enemy level).
There will be three different missions inside Vault 94, each of which will be active for a week before cycling on to the next. Each mission will also have three difficulty modes, with better loot on higher difficulties. Said loot will involve plans for new power armor, and a unique resource called Vault 94 steel for crafting them.
Vault 94 opens on August 20, as part of Patch 12. If you're looking for info on the Wastelanders update, which will bring NPCs to the wasteland, here's everything we know (opens in new tab).