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