is selling league accounts against the tos

Yes.

I'd suggest you read the ToU and EULA. These are two contracts you signed to make your account... and have to accept every single time you update. http://na.leagueoflegends.com/en/legal/termsofuse http://na.leagueoflegends.com/en/legal/eula

Terms of Use, Section III-D D. Account Sales. The Account supplied to you is personal to you, and Riot Games does not recognize and expressly forbids the transfer of user Accounts. You shall not purchase, sell, gift or trade any Account, or make any such offer, and any attempt shall be null and void. Any distribution by you of your Account and/or your Login Credentials (except as expressly provided herein or otherwise explicitly approved of by Riot Games) may result in suspension or termination of your Account.