Nar Demon Binder

Through years of study with the Demon Binders of Nar.  You have practiced and rehearsed you innate ability to dominate and control demons.  

When a summoned demon(s) fails its save against its compulsion to be controlled, in no longer gets to make a save at the end of its turn to resist its control. All demons summoned by you have disadvantage against its save to resist domination regardless if you know its true-name or not.   It will obey the summoner faithfully and to the best of its ability until the end of the summon spell duration. Further you can reduce the CR level of the summon demon spell by thee proficiency bonus of the caster.