GodZo's Azorius Fortress deck, that took the trophy for the final event of SPDC last season.
But to start out with, let's take a look at the key card for that interaction - Fate Foretold. This Blue Common is part of a cycle of Common Auras that replace themselves when they enter the battlefield. In general, this is good value, as the card always at least replaces itself, assuming of course it resolves.
Now what's interesting about this card is that it literally has no effect on the creature it enchants. Instead, it replaces the creature with another card when that creature dies. A build-your-own Runewing Drake, if you will.
The closest analog to this card is actually Altar's Reap. For the same converted mana cost, when the creature in question dies, you draw two cards. Clearly Fate Foretold is generally weaker, since it casts at Sorcery speed and doesn't give you control over when the creature dies.
Anyway, on to the interaction. What happens when you cast a Fate Foretold on a Keening Apparition?
With Fate Foretold enchanting Keening Apparition, you can sacrifice this spirit at any time to destroy the Fate Foretold, sending both to the graveyard and drawing a card in the process. You've spent two cards, drew two cards, and got some incidental value out of the creature. This is probably the low-end of this interaction. Chump blocking creates the same result.
On the other hand, if you use the Keening Apparition to trade with another creature, you've spent two cards, drew two cards, and sent an opponent's card to the graveyard. Essentially, you are up a card on that exchange. Using the Keening Apparition to destroy a pesky enchantment of your opponent's works in a similar way, and is probably the maximum value of this interaction.
So of what value is this interaction? Honestly, at the end of the day, it's about the same value as a Divination. You've spent a card that replaces itself and then draws an additional card. In doing so, though, you've taken on the risk of having the creature destroyed before the Aura resolves as well as never drawing the creature in the first place.
In the end, while using Fate Foretold may make your opponent hesitate to destroy the creature it enchants, that alone isn't enough to justify the risk and extra steps.
Of course, Fate Foretold does have one other advantage that might be enough to justify its inclusion. In a deck running Ethereal Armor, Fate Foretold also increases your Enchantment count; similarly, in a deck running Auramancer, you can retrieve Fate Foretold from the Graveyard to use again. Given the right draw, this can certainly be pretty sick value. But unless you're taking advantage of these synergies, Fate Foretold simply isn't worth playing.
Did I miss anything in my evaluation? If so, I'd love to hear about it in the comments below. And thanks for reading!