Assassin's Creed Odyssey keeps increasing in scope and content as we delve deeper into Ubisoft's post-launch plans, and the latest addition to the game is the Mastery Levels System, which allows for endgame tweaking of one's character build.
Assassin's Creed Odyssey Mastery Levels are introduced as a way to spend Ability Points after you've already reached level 50 in your current playthrough, and serve as a min-maxing tool for those of us who are inclined to fiddle with it.
According to Ubisoft, Assassin's Creed Odyssey was missing a way for players to spend their Ability Points after already reaching endgame, and the Mastery Levels System allows for them to do so! Investing points into any given Mastery will further increase its stats, thus optimising your character.
It is important to note that all of Mastery Levels are passive, and stack on top of one's character build, as well as weapons and other assorted gear. There are 72 Mastery Levels in total, with each Mastery being upgradeable up to 20 times.
Should you be unhappy with your investment or wish to alter your Mastery Levels, you can respec by spending drachmae, so there's no reason to be overly careful in fiddling with the new feature.