This card represents why hybrid mana is awesome. Remember Black Knight and White Knight? Yeah, this card is better than both combined, kinda of like a Megazord. Okay, it does cost more and it doesn't start with first strike, but those things are minor when compared to the overall usefulness of this card. Starting from the top, this card has protection from 40% of all cards in Magic and I'd be willing to bet that translates into over half of all kill spells (I've never done the math to be sure). It can also gain flying, something which black has a slight problem with (at least with cheap good flyers). The first strike makes this card a formidable attacker when combined with its next ability: firebreathing. As I mentioned in my Dragon Engine review, finding unlimited non-red firebreathing is nigh impossible (Dirtwater Wraith, Sea Spirit, Snow Fortress, Soldevi Simulacrum, Viscerid Deepwalker, and Wall of Water for future reference) so the cost is actually fairly priced. Now, the one drawback with this card is that it has no protection against red, which can easily throw a Lava Dart at it or any other direct damage (and yes, I do think that Lava Dart is 100x better than Geistflame).
Pros: Black Knight and White Knight Megazord
Cons: Weakness to direct damage