I think the fact that a card is a nationals promo should have no bearing on its power.
My reasoning: Rarity should not determine power. My reasoning for that is that it makes the game more about who can buy the cards they want rather than about the ability to build a deck and play well.
By making powerful cards rare all you do is manipulate supply (less rares are available than commons and such) and demand (the cards are in more top decks) to push the price of the good cards up and therefore decrease the number of players that can have top decks. (I'm not defining what a top deck is or anything like that, but I'm basing this on the idea that only N cards are going to make it into top decks and if many those N cards are expensive that will make top decks more expensive)
Split Altar is fine as it is, sure when it came out it would have been better had it included artifact piles, but now the big thing with Artifacts is having a bunch active with Temples and special activation artifacts (like Magic Charms and Iron Pan). Split Altar does a wonderful job of clearing out your opponent's artifacts at the beginning of an attack. If we really want to power up Split Altar it should be a Territory Class, that would make it much better than allowing it to shuffle artifact piles.
