I have no idea where to post this question: How does Riot feel about usage of their images?

So I run a League podcast and as we're growing I'm wondering about our usage of League content. We have an edited version of the League of Legends logo, we use their music on soundcloud for our outro music, and we want to create t-shirts to purchase that may or may not use some League related stuff.

So what can and can I be using? Can I get direction on who I may need to talk to or pose this question to?

Thanks!

JustCasual