Gift of Doom doesn't cost any mana to turn face-up and can save one of your creatures while you're completely tapped out, something your opponents won't anticipate often
Also using a deathtouch-granting card like Bow of Nylea can have massive effects with trample
In a way, this feels like a modal spell, and while most of the time this is killing off a two or three-drop, it has other implications as well
Mirrodin didn't have many typal cards, but it did do two things that provided a huge boon for typal decks
Whether you favor this new iteration or the previous Dissension printing Isperia the Inscrutable (the guild champion at the time) is all a matter of personal taste
What sets Choco-Comet apart, though, is the fact that its also a late game finisher