Vortex Elemental is a one-time effect, and one thats cheap and easy to pull off
Either way, he also untaps all your lands, which is way worth it
For example, it won't affect Flameblast Dragon's cost, since that's a cost paid when a triggered ability resolves, and it won't affect a kicker cost, since that's an additional cost to cast a spell
You can also cause your opponents to lose life or gain some life of your own with cards like Sheoldred, the Apocalypse and Starscream, Power Hungry
A player needs different colors of mana to cast different creatures and spells, and builds their deck around a single color or, more commonly, around a combination of two or more colors
Four mana to clear the mana rocks, the artifact creatures, and value pieces like Rhystic Study or Smothering Tithe is great