On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough of the Breaking the Order quest.
Reward for completing the mission: Thor's Cape.
Eivor agrees to help the Hidden Ones get rid of the Order of the Ancients from England to ensure the longevity and security of the alliances made by the Raven Clan.
Find and kill the members of The Order
In Assassin's Creed Valhalla, you have to eliminate a total of 45 people associated with the Order of the Ancients –15 zealots (mercenaries), 29 members of the Order, and 1 leader of the Order - the Grand Maegester: Information about the members of the Order of the Ancients and their whereabouts can be found on the separate pages of our guide. We divided them according to the Maegesters, i.e. the members of the Order of the middle level - most of them are subordinate to several people. Separate pages contain information about all the zealots/fanatics and about the leader of the Order – killing that person will ultimately end the Order of the Ancients' plotline.
Return the Order medallions to Hytham
All medallions taken can be successively brought to Hytham. When you bring back the last 15 medallions (along with the Grand Maegesters medallion), the mission Breaking the Order will end, and you will receive Thor's Cape as a reward.
There may be a situation where the game suggests you hand over the medallions collected BEFORE the Grand Maegester is revealed. Don't go to Hytham then because Eivor immediately exposes the leader of the Order of the Ancients. It will result in the inability to complete the game - no last story quests: The Letter and The Poor-Fellow Soldier.