The Far Wilds tries to make sure you are always able to increase your domain level. It does this by sometimes changing the next card you would draw. If you don't have a card that gives you domain in your hand and you don't have a domain building currently constructing you will draw the next card that gives you domain left in your Army.
This means if you are building an army you don't have to worry about putting enough buildings in to be able to randomly draw one when you need it.
As a result it makes it easier to play dual domain armies. For example if you have a Grove but really need a Mountain Folk domain you can discard the grove and hopefully draw a Dwarven Hall for your next card.