All of your nonlands are now artifacts in play, and elsewhere as well like you your graveyard, hand, library, Command Zone and exile zone
Cards that have a wide, sweeping effect (such as Grab Your Sword which deals two damage to all opposing characters) became extra powerful because they hit all three opponents at once
The infamous Sol Ring, Thought Vessel, and Mind Stone all give you colorless mana
Its not a bad ability at all, although its probably a little underpowered compared to the cards printed nowadays
The Heart of Magic can be played without a grand strategy in mind
And finally, one of the better Merfolk commanders to ever be printed, Kumena, Tyrant of Orazca, is also included in case you want to swap out commanders, giving you some incredible power in the Command Zone.