The Assassin mastery is useless compared to Secret Stash
The Assassin mastery is pretty much useless and worthless even for top and mid laners. The Secret Stash mastery offers a much better value than the Assassin mastery. Secret Stash regenerates your health and mana faster, and this is obviously way better on almost every champions. On the other hand, Assassin only makes you deal 2% extra damage only when you're alone, which is pretty much unnoticeable when you compare the amount of sustain Secret Stash gives. Let's say you were dealing like 200 damage per attack without this mastery, you'd only deal 4 more damage with this only when you're alone. And by mid and late game, you'll be with at least one teammate most of the time, so Assassin will have no effect later. I know you don't really buy potions later during a game, but it's way more useful during laning phase than the unnoticeable amount of extra damage Assassin gives. This Assassin mastery should either be buffed (like to 5%) or be replaced with a different mastery that'd give much better value.