The The Fate of Atlantis Add-on for Assassin's Creed Odyssey has 15 achievements.
Kill 10 Isu Soldiers with the Blessing of Kronos enhancement.
Defeat the Hekatonchires.
Forge the 3 Legendary Weapons.
Collect all the Keeper's Insights in Episode 3.
Completely fill the Knowledge Sequence.
Dethrone the king.
Close all Tartaros Rifts.
Defeat all of the Fallen.
Collect all the Keeper's Insights in Episode 2.
Defeat Cerberos.
Win the conquest of Elysium with freed humans from the 3 main regions.
Collect all the Keeper's Insights in Episode 1.
Destroy all of the Marble Maiden Tributes.
Remember who you are.
Kill all Overseers in Elysium.