Xerxes Thanks for the response. I found level.custom_random_perk_weights in include_perks_in_random_rotation, and it looks like this:
level.custom_random_perk_weights = ::tomb_random_perk_weights;
Is this just a simple reference to a function that can be called via custom_random_perk_weights later, or does tomb_random_perk_weights get called and referenced when this code is run?