Karthus Free Revive on Ascension

In order to become Ascended, you must stand on the buff (similar to picking up the Rift Harald buff). However when Karthus is dead, he can still become Ascended as long as he dies on the buff, due to his passive keeping him there for a few seconds. In the video, you see me die and my death counter increases as soon as I go into passive. But I pick up the buff anyways and instantly revive where I died, as the Ascended.

You can cheese this way too, it's easy to replicate. Just wait for the Ascended to die, and get there before anybody else (In the video I flash to get there). If you don't want the hassle of other players, you can do this in a custom with a friend.