Sanctum of Domination is one of the three raids available in fated mode during Season 4. All bosses once again drop a variety of relevant gear with upgraded ilvl. Ranging from 278 in normal, 291 in heroic and up to 304 in mythic, buying full gear in Sanctum of Domination is the best way to boost the character performance in S4.
This service includes gear not only from Sanctum of Domination, but from two other raids (Sepulcher of the First Ones & Castle Nathria) as well. Only one fated raid is active per week, so it is nearly impossible to farm gear only from Sanctum of Domination as this instance is active only once per 3 weeks.