This one's legit. The source is the Wizards of the Coast page. Besides, this looks a lot better than the debunked fake. That one had the right art, but that was about it. Remember that trashy-looking forgery? It was a nightmare. How are players going to know what "Turn target permanent face down" means? Does it make a creature into a morph creature? If the creature already has morph can you turn it back up for its morph cost? The templating was off, too. Still. despite being a sloppy mess, this card was convincing enough to fool Gathering Magic and that site ran a story confirming the card.
Real Ugin seems pretty sweet. Is he better than Karn in tron decks? Hard to say. His ultimate is less punishing in that deck in particular and his plus ability is also worse compared with Karn. Where Ugin shines is his -X ability. If X=3 against most decks in Modern, you're wiping their board like a ShamWow.
Do I expect Ugin to get the nod over Karn? Not necessarily. Karn is still very, very good and Ugin needs to be seen in action before we can determine its full impact. I think if this presells over $30, stay away. I also don't expect it to not presell over $30 so I think we try to crack this in packs and trade into them at peak supply. If this does become a $50 card it will be a $20 card first. That I'm almost positive of.