I am unaware of that tradition though am familiar with its name amoung other traditions like Zoroastrian and Kemit etc.
http://www.hourofthetime.com/1-LF/Dec%2014/The_Mysteries_of_Mithra_1903.pdf
CTRL+F Mithra on this page is a good summery
https://viefag.wordpress.com/2011/12/15/mystery-babylon-bill-cooper-hour-9-initiation/
For some reason I thought of the saying "Mirth is king" With the royal order of jesters. Perhaps Mirth is really Mithra? Maybe not but freemasonry does claim to be the current version of the ancient mysteries and the cult of mithras was one of those traditions.
Mithras was featured in a film called "the conspiracy"
So a modern day version of that was imagined like this https://youtu.be/WRUXh8Gn4KY?t=3529
Now its asinine to try and deduce a modern day version of this cult from a horror movie but the movie shows an initiatic hunt wherein they slay a man. Very much what one would expect a la the aztecs rolling heads down pyramids.