So, I'm assuming Mr. Marc "Tryndamere" Merrill is a big fan of Back to the Future movie series

This is probably old. But I'm very sure that Tryndamere's "Mocking Shout" ability is a big reference to the the chicken scene in Back to the Future movie series. The mechanic of the spell resembles that extremely well, including the chicken icon on enemies turned back.

Since the champion was named behind Mr. Marc Merrill who is the president of Riot, I'm assuming he wanted such an ability on the champion that has his name, probably because he is a big fan of the movie. Maybe.

I have included a video reference to check out too.