In life you heard ramblings in your head, even in death they stick with you. The path of the mad is only open to some, but those who take it have more power than any could comprehend.
Your inner ramblings have spread outside of your mind. Through time you have found it possible to hear and speak to those of great power in hell. Secrets of their knowledge can fill your mind when you attempt to search for secrets. When rolling investigation or perception checks, you may prick your finger dealing 1d6 bleed damage to automatically succeed the roll. Also if something attempts to harm you by taking control of you through your mind in combat, you have advantage on the saving throw thanks(?) to your madness. These come at a cost however, once per combat you have a chance to go mad for a round and skip your turn. (DM rolls)