While all Isshin decks want to attack, this is another commander that you can build in a few ways, as there are loads of strong creature cards to choose from, and plenty of room for building up subthemes
The point is that once it hits a certain threshold of usefulness, its not at all unprecedented for a rare from New Phyrexia to be $10, or even $15
While Oko has synergy with the deck, both in terms of having a lot of low-impact cards to upgrade to 3/3s and creating artifacts that become Mox Sapphire when Urzas on the battlefield, Urza strategies are extremely high-synergy and generally not looking to attack with 3/3s as a meaningful part of their gameplan
Sebastian Rosenauer This is a card I have little experience playing with myself, but I have sat on the other side of the table often enough to know how powerful the elemental can be
Plus, opening up to black also doubles your chances of finding efficient beaters that fit into Oboshs odd-CMC requirement like Kederekt Parasite , Pestilent Spirit , and Syr Konrad the Grim
The flagship commander is 'The Wandering Horse'