The main story centers around a wealthy man with a dark past that starts an underground fighting pit to offer blood and sacrifices to the gods. He's shown to have ties to some sort of dark figures (possibly demons or evil gods). The series has magical items, a dragon, an alien, and much more. Seriously, this is some good stuff.
The first two seasons are on Netflix. Considering season 2 debuts on El Rey tomorrow, I really hope season 3 shows up on Netflix soon.