Sure you won't always hit cards of mana value 6 or better, but it's a pretty good mana sink
Omnath, Locus of All can draw ultimatums faster and give you extra mana, and General Ferrous Rokiric gives you a big golem
The value of X won't change even if the number of lands you control changes after that point
$1.79 Child of Alara From the Vault: Annihilation $0.99 Garth One-Eye Modern Horizons 2 $4.99 Nicol Bolas, God-Pharaoh Hour of Devastation $0.59 Mindleecher Commander 2020 $1.79 Songs of the Damned Ice Age $1.79 Progenitus (Grand Prix Foil) Promotional $2.49 Progenitus (1163 - Foil) Secret Lair $1.79 Rafiq of the Many From the Vault: Legends $1.79 O-Kagachi, Vengeful Kami (Foil) Commander 2017 $9.99 Scion of the Ur-Dragon Time Spiral $0.59 Jodah, Archmage Eternal Dominaria $13.99 Kynaios and Tiro of Meletis (Foil) Commander 2016 0 results found
If you do, draw X cards, then put up to X land cards from your hand onto the battlefield tapped, where X is the sacrificed creatures power. Being able to throw away some of your cards for not just extra cards in your hand but also extra land in play is game-winning
