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