Green Witch's Emerald Amulet

Green Witch's Emerald Amulet enters the
battlefield tapped.
{t}: Add {g}.
Rainbow: (As long as one mono-color permanent of
each color is in play, the game has rainbow) Sacrifice
Green Witch's Emerald Amulet: Search your
library for an Enchant Creature, Enchant Land
or Enchantment Creature card. Reveal it,
shuffle yourlibrary, and put the card on top of it.
"Within it sleep the seeds of a thousand spells of
strength, and vigor."