(In this case, how many lands are in the deck.) The third field will be how many chances you will get to find that card, via drawing cards
If not, even the single card you're most after can be sent back, and sometimes it's more important to get a good mix than it is to find any one card in particular
If you need to catch up, you can start at the beginning with The Basics, or see the most recent installment, Steps Of A Turn
It has an artifactfall ability that turns new artifacts into removal, though being the only black modular card means it doesn't have as many homes as the rest of these cards
Though technically you give it a colour at the start of the game, it has no inherent colour of its own and costs five generic mana.
What affects the value of Voracious Vacuum