Zana's former colleague Veritania has been driven insane and is lurking in the Atlas. Search Maps in the corner Regions of the Atlas to find and defeat her.
Open a map that's in in one of the corner regions of the Atlas (Haewark Hamlet, Lex Ejoris, New Vastir, Lira Arthain). The third time you do, Veritania will appear and taunt the player, adding her influence within the map region. Repeat this two more times, then talk to Kirac. He will show the location of the Citadel in the region, then talk to Zana to open six portals into Veritania's Citadel. After defeating the map boss, go into the portal and defeat Veritania, the Redeemer.
To spawn the Conqueror again, open a map in a region with one Watchstone slotted with a map of the appropriate tier (as long as their corresponding Watchstone hasn't been found yet for that region). Find their Citadel again by running maps within the region they're influencing two more times, then repeat the process of entering their Citadel and defeating them. Repeat this process with another Watchstone. After the fifth time, the Conqueror will be defeated, completing the quest. They will not appear again until you have challenged Sirus.
Cobalt WatchstoneCobalt WatchstoneThe memories and emotions of countless victims of the Elder, locked in stone for eternity.Socket this into a Citadel on your Atlas to increase the Tier of Maps and reveal hidden Maps in that Citadel's Region. You can only socket one Crimson, Viridian, Cobalt or Golden Watchstone into each Citadel.
Crimson WatchstoneCrimson WatchstoneThe memories and emotions of countless victims of the Elder, locked in stone for eternity.Socket this into a Citadel on your Atlas to increase the Tier of Maps and reveal hidden Maps in that Citadel's Region. You can only socket one Crimson, Viridian, Cobalt or Golden Watchstone into each Citadel.
Golden WatchstoneGolden WatchstoneThe memories and emotions of countless victims of the Elder, locked in stone for eternity.Socket this into a Citadel on your Atlas to increase the Tier of Maps and reveal hidden Maps in that Citadel's Region. You can only socket one Crimson, Viridian, Cobalt or Golden Watchstone into each Citadel.
Viridian WatchstoneViridian WatchstoneThe memories and emotions of countless victims of the Elder, locked in stone for eternity.Socket this into a Citadel on your Atlas to increase the Tier of Maps and reveal hidden Maps in that Citadel's Region. You can only socket one Crimson, Viridian, Cobalt or Golden Watchstone into each Citadel.
Ivory WatchstoneIvory WatchstoneThe memories and emotions of countless victims of the Elder, locked in stone for eternity.Socket this into a Citadel on your Atlas to increase the Tier of Maps and reveal hidden Maps in that Citadel's Region. You can only socket one Crimson, Viridian, Cobalt or Golden Watchstone into each Citadel.