Rivan, Cursed by Life

As an additional cost to cast this spell, sacrifice
three lands.
As long as you have at least 5 more lands in your
graveyard than on the battlefield you may play
permanents from your graveyard.
Sacrifice three untapped permanents you control:
Add X mana in any combination of colours to
your mana pool where X is equal to the total
number of lands in your graveyard.