We continue mulling through the newly released, complete Dark Ascension visual spoiler here with card number 89 of 158:
I like it... I'm just not entirely sure why I like it yet. Most of the time his untap ability is going to be useless, but when it works, I think you can really make it work. In other words, I think he's a build around card for both limited and constructed play.
In limited, the more creatures you pick up with flash, the better. This means that if you pick up a copy of Midnight Guard in your first pack you're going to want to be on the look out for cards like Ambush Viper, Midnight Haunting, and Hollowhenge Spirit. Once you get the ability to untap the guard at instant speed, he suddenly turns into a combat trick. And in limited, this is always a good thing.
In constructed, it's less about combat tricks and all about combos...
I don't play Standard or Modern, but I know all about Splinter Twin Decks. But you can tell me if red/white would be superior to red/blue Splinter Twin because Midnight Guard can essentially take the place of Deceiver Exarch to get the combo going.
I guess Midnight Guard only works with Splinter Twin and not Kiki-jiki, Mirror Breaker, but maybe there is still some potential for something new?
(This will require further investigation.)