Oracle Text

Equipped creature gets +4/+0.

RW, Unattach Sunforger: Search your library for a red or white instant card with converted mana cost 4 or less and cast that card without paying its mana cost. Then shuffle your library.

Equip 3

Card Rulings

10/1/2005 You can’t pay the cost of the second ability unless Sunforger is attached to a creature.
10/1/2005 Any card you find must be legally castable (for example, you have to be able to choose a legal target for it). If you can’t find a castable card (or choose not to), nothing happens and you shuffle your library.
10/1/2005 The card is cast from your library, not your hand. You choose modes, pay additional costs, choose targets, etc. for the spell as normal when casting it. Any X in the mana cost will be 0. Alternative costs can’t be paid.