Changing of the Seasons

When Changing of the Seasons enters the battlefield, spells and abilities that would add colored mana to a players mana pool add that much green mana instead, until end of turn.
At the beginning of each upkeep, repeat this effect by replacing the color of all mana produced with the next color in this order: White, blue, black, red and green, for as long as Changing of the Seasons remains on the battlefield.
"The winds of change blow swiftly in this part of the world."