Pulse of Llanowar

Enchantment

If a basic land you control is tapped for mana, it produces mana of a color of your choice instead of any other type.

"Gaea's memory is eternal, and she exists in all things."
—Molimo, maro-sorcerer

2004-10-04 This does not change the amount of mana gained. It just makes all the mana generated by the basic land be of a single color of your choice.
2004-10-04 You can choose a different color each time a basic land is tapped.
2004-10-04 You can choose the same color or mana the land would normally produce.

Card is in preconstructed decks:

mtg.wtf