Sure, you need 21 Druids out to steal all lands from all players in a single turn, which is going to be a bit harder to accomplish
If your deck is trying to cast as many X spells as possible every turn, and wants X to be as much as possible, we probably want to prioritize ramp more highly than just 8 or 10 spells - in fact, I can see running 60 mana sources, like this Vaevictis Asmadi, the Dire deck
But it is generally acceptable to use proxies in casual games with friends
Etherium Sculptor 3/10 A nice way to increase your burst potential but needing blue mana makes it quite hard to pull off with any consistency
Reiki, the History of Kamigawa draws cards, Saryth, the Vipers Fang gives your creatures deathtouch or hexproof, Zopandrel, Hunger Dominus doubles power and toughness, and Ghalta, Stampede Tyrant gives you an army for free