Assuming its largely the same as that game, it will be free to play, and players will be able to import physical cards to their digital decks
The Behemoth has haste to swing on the turn it arrives, and the Cavalry has flying permanently, so it's always evasive
It represented the Phyrexian invasion, which took place across many planes in the Multiverse
So if you can keep your commander in play you get benefits from your backgrounds, plus the powerful effects from cards like Skyhunter Strike Force for a massive melee, Tyrant's Familiar to burn off creatures, and Thunderfoot Baloth to finish opponents with a permanent, only slightly smaller Overrun
Some of these cards will be Eternal Legal, introducing a bunch of new wacky things for Commander