They arent a part of the actual game
(Quick answer: 42 + Sol Ring for a 2-mana Commander, 38 + Sol Ring and 9 other rocks for a 6-mana Commander.) He also considered an assumed curve, with a set number of 2-, 3-, and 4- drops and the like
Assuming you've not played any lands this turn yet, you can combine Azusa's ability with Ramunap Excavator's to play those three islands straight out of your graveyard
This archetype is most commonly used to refer to bringing creatures back from the graveyard, but there are many cards that focus on returning artifacts, enchantments, and lands as well
However, for all it's worth, it doesn't do that here
You may not need to get up to seven ink to win , especially if you haven't found one of the only two seven-cost cards in the deck