Through fair means or foul, you have discovered a way to summon demons without the use of spells. This power can surely not be used for good...

To summon a demon you require 100 humanoid sacrifices per CR of said demon, The demon isn't bound to you by this ritual and will probably not be friendly towards you. Though, if you have the fiend tag you may roll a [roll]1d20[/roll] to determine if the demon becomes loyal to you. the dc being 15-level

This feat also gives you an easier time identifying demons, giving you advantage to checks to determine information about them.

Now go! and make friends demons.