If a card specifically states that it moves Commanders from the battlefield to the Command Zone, anything that's been mutated onto your Commander moves along with it, then falls off - and will probably be stuck there, since there's no way to cast non-commander creatures from the Command Zone
Now which one was it? Flearan One-Eye, goblin engineer Illustrated by Filip Burburan Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp
Yes, theres a lot of ifs there, but the potential is also there
It also seriously messes with suspend, which was kind of the point
Many players agree that [c]Black Lotus[/c] is one of the most powerful cards in MTGs existence
Teferi draws you a card with his +1 and untaps two lands