Each week of Season 4 of Shadowlands will focus on a different fated raid: Castle Nathria, the Sanctum of Domination or Sepulcher of the First Ones.
When a raid is declared fated, all bosses will be equipped with a special affix, thus increasing the difficulty of all Shadowlands raids from now on.
As an extra, you have the option to upgrade your items to Heroic or Mythic. You can upgrade your items with shards that have a 100% drop chance from bosses. You need 20 of these shards to upgrade the item.
On Normal, the gear is raised to 278-285. On Heroic 291-298 and in Mythic Raid even 304-311.
Complete all three Shadowlands Fateful Raids in Season 4 and receive the Jigglesworth sen mount reward and the Fates of the Shadowlands Raids achievement.
On Heroic, you also receive an epic title for your WoW character "<name>, Hero of Destiny".