See Challenge # 113. We had a number of entrants that cared about how much mana you made, and I wanted to make a few cards about how far into the game you must be. After making this, I did think about having this card instead talk about card types in the graveyard, to get even more bonuses. Then I realized I was designing Tarmogoyf...

I guess I don't understand how this fits the challenge. Are you considering controlling certain permanent types to be a cost?

I happened to mention the problem on the page for Challenge # 113. I just misunderstood the challenge, and had to go back and make a different card. I was making a card that got better 'as the card increases'. I should have realized that that meant there was a numerical increase in the cost involved, but my mind was already designing cards by that point.