Sure, he would make a fine commander for a mono black deck but I think there's a case to be made here
While Myrel is on the lower end of the most valuable cards now, dont be surprised if it continues to climb once The Brothers War stops being printed
No, some are just pointy-eared mana finders like Greenseeker, or blunt-eared mana reanimators like Groundskeeper or even Snake-eared mana boosters like Sakura-Tribe Scout
Limiting its trigger to once per turn prevents it from becoming overwhelming, yet the card remains a reliable draw source in any counter-based strategy
it doesnt modify the trigger itself
Theres potent synergy there with cards like Dying to Serve, Drake Haven, and Cryptcaller Chariot that make tokens when you discard cards, allowing you to discard more cards next combat