mtg shadow cards of the Second Sun (MH3-070) - Modern Horizons 3 You may cast spells from among those cards for as long as they remain exiled The 18 Best Shadow Creatures

Since Isshin isnt really any of those, it doesnt qualify

If your commander would be put into your graveyard or exile, it goes there as normal

As you can see, Mockingbird is selected to go to the bottom of the deck

She's a great commander but you'd need to retool a lot of the deck for her to be better than Urza here

Sure, some of them are better than others, but they have been relatively balanced (especially over the past few years)

As such, Lita, Mechanical Engineer will always untap your Vehicles before they go back to being artifacts, allowing you to use them offensively and keep them able to be used as blockers later