A League account.

It was a day in June my friend decided to chat with a stranger on my account while i was asleep. The guy want's to get boosted and he accepted it. So now i got his information for his league account. The account itself looks like it's bough but what do i know? It was Platinum in Season 3 and this guy can't even climb out of Silver. He's to bad to be an old player basically.

So i was thinking, is it something bad you can do with this account? I really don't mind boosting others but boosting that guy feels wrong.