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