During a blood moon, NPCs grouped together no longer push back monster spawn areas and zombies can break down doors, so you might want to protect your merchants. Oh wait, wrong game. Shadow Era time!
Dark Prophecies 81/150 - Blood Moon
Spoiled by Kyle on 12/24/2012
One card for three is simply a powerful trade. This may take a while, be subject to removal, and keep Moonstaler unprotected (although its allies still are), but it's still 3 cards for 1 for a mere two resources.
There aren't a lot of interactions, here. It's not like wulven have Shrine of Negatia or some other trick for recycling. This is, pure and simple, a good card. The cost is cheap enough to drop it early or under a Jeweler's Dream, and the effect is a simple card exchange.
One thing worth noting is that Full Moon doesn't actually grant stealth, just a damage shield. Those two cards WILL stack, just not Blood Moon and Millstalker's ability.
The only real problem with this card is that the draw isn't as fast as other options, rolling in over time instead of all at once. However, due to the strict hand limit, that could also easily be a good thing. You can drop this card on the second turn, on the draw, and still get the full effect out of it if you want.
8/10. There's nothing wrong with good, cheap card advantage. Unless you're Millstalker, and Wulven Studios has said multiple times that this set will cripple Millstalker anyways, there's not a lot of reasons to skip playing this card. Even if Moonstalker is your hero, not only will Full Moon do the trick, but it's not like you can't use your ability. Blood Moon just becomes +1 card instead of +2. That option isn't lost. The fact that this is a bit slow, despite the aggressive cost, means it might not always be the best choice for every deck. My feeling, though, is that this card will be the rule, not the exception.
(By the way, it's a Terraria reference, if you still don't get it.)