Warpstone Excavation is a strong card that allows the player who starts a considerable advantage. In AGOT, locations provide income (gold) are Limited or Limit 1 for deck. So, why not make these changes?
Text: Limited (you cannot play more than one limited card per turn).
Your units enter this zone corrupted.
Forced: When this zone takes combat damage, sacrifice this card.
Limited (you cannot play more than one limited card per turn).
Thank's for your attention. I hope that I have not made many enemies.