I retract my previous statement. Sated is broken, at least for Vayne. Lemme tell ya why. I have only actually played Vayne twice in a real game before Sated came out. Scores those games were pitiful, 12/12/4 and 4/11/8. Then I go into a game as Vayne top with Smite. By the time I finished BotRK I had Sated Devourer, and I went 13/7/5. Half of those deaths were to me fucking around, as was the loss of the game. Vayne with Sated is, in fact, broken. I just didn't realize that before I played it. And it's not just a case of "Oh, well, your enemies were ass," because, again, I have no idea how to play Vayne. I played her once in March and once in May when she was free. Other than those and a custom to test Sated, I had no experience. Along with that, I'm a B5 player, easily. But then I go into a game and go 13/7/5 because of a new item? It's broken.
Now. If I were playing Jungle, it woulda been a lot easier to shut me down. But I was in a lane. So I just went and got stacks when I felt like it. And even the best junglers don't have the time to kill every large monster and every scuttle crab in both jungles before I have a chance to, so getting Sated is easy. The enchantment is broken on some champs, Vayne included. Period.