Possession

You just need to have verification that you bought Kayn before his release.

In a manner similar to how drunks are liable for their behavior, you'd still be liable for what was done using your body.

Even if you persuaded Riot that it was an entirely different entity, then you'd be guilty of account sharing, and that's a permaban offense.

In terms of the ToS, the onus falls on the account holder to secure the account. Any actions that happen on your account are your responsibility. It is your duty to ensure there is no way the ghost who possessed you would know your password.

That's why I use a password manager for all my passwords. Not even I know my own League password, thanks to the advancement of technology. Services such as LastPass or KeePass are what you're looking for. There are many out there, so do some research and find the best one for you.

Good luck out there.

No, Twin Shadows was removed long ago

You know, if you reworded this, it could be some quality M&G material.