Citadel

There are three types of Citadels, each located in different cities throughout Wraeclast. Copper Citadels in Faridun Cities, Iron Citadels in Ezomyte Cities and Stone Citadels in Vaal Cities. Complete one of each type of Citadel and collect their Crisis Fragments to gain access to The Burning Monolith.

Atlas passives

Bring Me Your Leader
Summoning Circles in City Areas have 5% chance to instead summon a random Citadel Boss
Warlord's Vendetta
Invaded Cities have a 20% chance to include an invading Citadel Boss fighting the Map Boss