Recursion as a Cost

So I've been thinking of ways to facilitate recursion in Overgrowth in a way that feels natural in order to make the reave mechanic work well. Even though reave is only going to be in black/red/artifacts, there needs to be recursion in all five colors for a limited setting. So somebody playing green/black has choices to trigger reave, for example.

The graveyard is an extremely limited resource compared to the library or even the hand early in the game. What if graveyard recursion wasn't just a benefit, but also a cost that needs to be considered?

So it's significantly undercosted if you're able to pull a land card out of your graveyard. Otherwise it's overcosted.

My initial concept was that it didn't have the either/or option. You had to have a land in your graveyard to put on top of your library or your couldn't play it at all. That felt way too disappointing if you didn't have a way to sacrifice a land, especially for a card in a rare slot. So I added the the double-green option. You'll still be very unhappy to have to pay six mana for this, but it's better than having it dead in your hand.