Can I legally sell this online???

As I mentioned in the title is it possible for me to make my own splash art (e.g. a shadowy nocturne image on a shirt and sell it? WITHOUT USING THE "League of Legends" title ANYWHERE. Simply just a drawing). Can I legally sell this online, and to friends???

If there are any requirements OR payments necessary please mention below in the comment section.

RIOT Member answer please! Thank you very much!!!

THE LINK GIVEN ISN'T MINE! Just an example that I found online.