Fertilizer

{t}: Give a friendly creature with the Plant tribe +2/+2 until the end of this turn

{t}{g}{g}: Give a friendly creature with the Plant tribe +4/+4 until the end of this turn

{t}{g}{g}{g}{g}: Give a friendly creature with the Plant tribe +2/+2

{t}{g}{g}{g}{g}: Sacrifice this artifact, gain a colored mana for each untapped source of mana you control