Are we allowed to create league merch with champion pictures/slogans?

I've been thinking about making some merch using my own designs, but these designs include champion pictures/slogans which I assume are considered intellectual property of Riot. Would it be illegal to make the merch? I'm assuming to sell it I would need some sort of licensing from Riot (would that be possible, do they ever do that for independent sellers?), but I figure just making it for myself might be okay. Any help is appreciated, thanks!