If you arent aware, you completely exile an opponents library with Helm of Obedience and any one of those, which is certainly potent
You get what kind of deck Goblin King is going to lead to
Also, Kardur is one of those rare commanders that you dont want to play ASAP
1 Unfinished Business
They included Vanguard of Brimaz (Born of the Gods, 2014), Eternal Dominion (Saviors of Kamigawa, 2005), Pegasus Stampede (Tempest Remastered, 2015), Oubliette (Double Masters, 2020), Man-o-War (Modern Horizons, 2019), Brothers Yamazaki (Champions of Kamigawa, 2004), and Brain Freeze (Vintage Masters, 2014)
The Mega ex cards themselves are worth having at your disposal, each offering a vastly different playstyle