We continue mulling through the newly released, complete Dark Ascension visual spoiler here with card number 87 of 158:
An excellent limited card. A potential constructed mechanic?
I still stand by my statement and say that Fateful Hour cards are only good in formats where there are efficient, complimentary cards that allow for intentional lose of life. You have to be able to turn Fateful Hour "on" whenever you choose to turn it on. There are plenty of cards in Legacy that would do the job and many of those cards are from Scars of Mirrodin's phyrexian mana, so it might be viable in Standard as well. But in Innistrad Block, when and if it turns on is left to your opponent's actions and because of that, I just don't think it's that good.
If we're going for a white weenie deck, I'm kind of feeling the Form of the Dragon Fateful Hour Deck. Add Gavony Ironwright to Faith's Shield, Gather the Townsfolk, and Thraben Doomsayer together with cards like Gut Shot and Spellskite and you'd be playing with overpowered, undercosted Fateful Hour cards with the ability to deal 5 damage every upkeep to any target while creatures without flying would be unable to attack you.