The created card doesn't necessarily need to be from your deck, library, or sideboard, and could be a card in another set or format, as if it was created "out of thin air"
Its part of another spell or ability resolving
It's an open-ended question, but if you can't answer it everything else in the deck won't matter
One important note before we move on, though: the amount of ramp in your deck and the amount of treasure generation can free you up for playing more enters-tapped lands, as this allows you to be more mana efficient
They don't go away as steps, phases, and turns end, and effects that add mana "of any type" can't give you energy counters
I have yet to see someone open their fifth copy of a rare or mythic, though, so I dont know how much Vault progress those will give you