Here is the full list of all 99 Mist Legacy achievements.
Defeat Zhyxhu.
Learn to peer into the Mists.
Complete the Militia Introductory Quests.
Recruit Ovie.
Build a first paddock.
Recruit Corrin Fortvaillant.
Build a first barracks.
Defeat the Aquagremfyr.
Build a first shelter.
Build an outdoor workshop.
Build your first cart.
Help all of the scribe's friends.
Activate the Kortombe portal.
Complete the tower construction quests.
Complete the introduction on the Troll Plateau.
Activate the Troll portal and come back to your domain.
Recruit Finn Vorel.
Recruit Badouk Brank.
Recruit Palenne Roirdan.
Defeat Tortolus.
Defeat Valdiss.
Defeat Rayth.
Defeat Arriel and Ela.
Defeat Hoboturla.
Activate the Wellnear portal.
Activate the Whisper Portal.
Activate Corinna's portal.
Activate the Enorwen portal.
Activate Thorval Portal.
Activate the Gantras portal.
Activate the Leviathan portal.
Activate the Prettybard portal.
Activate the Chimeric portal.
Activate the Norkantas portal.
Activate the Grandfall portal.
Complete Sorka's quests.
Investigate your first ruin with the druids.
Learn the basics of magic with Yolasula.
Be accepted at Fearpiercing Camp.
Save Ouab and become a herbalist.
Complete the quests related to the Scabonzis.
Complete the collector Innkeeper quests.
Reach the Fort of the Mistwalkers.
Be recognized in Kortombe.
Be invited in Wellnear.
Be familiar in Larcen.
Be recognized in Gantras.
Be seefeets in Thorval.
Defeat Ilmagoth.
Defeat Bobu.
Defeat the Scabonzi guardian protector.
Defeat the Great Protector.
Defeat Gularzob.
Build a first workshop.
Build a first herbatum.
Build a first dispensary.
Build a first forge.
Build a first cutting plant.
Build a first sawmill.
Build a first tannery.
Build a first studio.
Defeat Serassert.
Pass the door of justice towards Gantras.
Enter Giltanbourg.
Complete the Alchemy Learning Quests.
Integrate the guilds of Ordval for Leonidas.
Complete the Lithofortress.
Evolve Ovie.
Become an apprentice Arcanist.
Become a claw in the Assembly.
Become a wanderer of the Lunar Caravan.
Become acolyte of the Circle of the Great Tree.
Become a Messenger of the Order of the Hippogriff.
Become squire of the Protector of the Rose.
Defeat Whuzulm.
Become Mistwalker
Defeat heroic Whulzum.
Defeat heroic Gularzub.
Defeat the Cybelfly Queen
Evolve Finn.
Defeat Hilla
Defeat Hazko.
Buy the flame frame.
Build a first warehouse.
Defeat heroic Hazko.
Defeat Rylenback.
Defeat the Tarascarpel.
Defeat heroic Rylenback.
Defeat Eli'carde.
Defeat Tarathiel.
Defeat heroic Tarathiel
Defeat the army of darkness.
Defeat Cyclotus.
Complete the adventures on the island of Tinylegs
Defeat Ezhilya.
Defeat Mo'gul.
Defeat Walkrock.
Defeat heroic Ezhilya.