The Great Booster Pack Tree

{u}{g},{t}: Put a growth counter on The Great
Booster Pack Tree.
{1}{u}{g}, Remove 3 growth counters from The
Great Booster Pack Tree: Open a sealed Magic:
the Gathering booster pack.
You may cast spells from booster packs opened
with The Great Booster Pack Tree, and you may
spend mana as though it were mana of any color
to cast those spells.