For example, if your commander is [c]Kess, Dissident Mage[/c], you can only play blue, black, and red cards (or cards that are a combination of these colors)
Those are the most expensive cards in Dominaria United
It doesnt have the ability to clear the battlefield like By Force and Release the Gremlins, but Manglehorn might be of increased interest too
[20] The Dual Lands: Tundra , Underground Sea , Badlands , Taiga , Savannah , Scrubland , Bayou , Tropical Island , Plateau , and Volcanic Island
End aside As we said in the very first sentence of this article, (self-contained) two-for-ones are relatively common
Flanking means: Whenever a creature without flanking is assigned to block this creature, the blocking creature gets -1/-1 until end of turn