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With the archangel Avacyn still missing in action and the protective wards of the Avacynian church fading in power, the plane of Innistrad is starting to get a lot... darker. Dark Ascension brings new weapons for monsters and innocents alike and builds on the mechanics and themes of Innistrad.
Undying is a new keyword in Dark Ascension that lets creatures come back from the grave stronger than ever.
When your undying creature with no +1/+1 counters on it dies, you'll return it to the battlefield with a +1/+1 counter on it. An undying creature that has one or more +1/+1 counters on it when it dies stays in the graveyard as normal.
It doesn't matter where the +1/+1 counters came from, or whether a creature has already come back with a counter on it; all that matters is where the counters are when it dies. If your undying creature gets a +1/+1 counter on it (say, from Travel Preparations) and then dies, it won't come back, even if that's the first time it died. On the flip side, if you can get that +1/+1 counter off of an undying creature somehow after it comes back, it'll come back yet again the next time it dies. Undying indeed!
If a creature ever has +1/+1 counters and -1/-1 counters on it, the two kinds of counters immediately "cancel out," one for one, until only one kind of counter remains. For example, a creature with three +1/+1 counters and two -1/-1 counters would end up with one +1/+1 counter. There's a twist, though: If a creature with +1/+1 counters on it gets enough -1/-1 counters to kill it, it dies before the two counters have the chance to cancel out. For example, if your Strangleroot Geist with a +1/+1 counter on it got three -1/-1 counters from Skinrender's "enters the battlefield" ability, the Geist would die with one +1/+1 counter and three -1/-1 counters and wouldn't return to the battlefield.
They say the night is darkest just before the dawn, and the new fateful hour ability word in Dark Ascension takes that philosophy to heart.
Fateful hour abilities work as long as you have 5 life or less. As soon as your life total drops to 5 or less, they immediately kick in. So you could pay some life to an Immolating Souleater in the middle of combat to suddenly give your team a boost with Thraben Doomsayer. As soon as your life total becomes 6 or higher, fateful hour abilities stop working—so gaining life with Thraben Doomsayer on the table might cause your creatures to get smaller in the middle of a turn.
Other fateful hour abilities may be triggered abilities, static abilities, or abilities that change what an instant or sorcery spell does.
Like Innistrad, Dark Ascension features double-faced cards—cards with no Magic back and a face on each side. In Dark Ascension, however, not all of them are creatures.
For the nitty-gritty details (including how to draft with double-faced cards) and weird corner cases, check out the Double-Faced Card Rules Page. We'll cover the basics here.
Double-faced cards in general
A double-faced card has two faces. It has no regular Magic back. Its front face, which is marked with a sun symbol and has a mana cost, is the default. A double-faced card always enters the battlefield with its front face up unless an effect says otherwise. This is true whether it enters the battlefield from the stack as the result of being cast, or from anywhere else, such as your graveyard (due to a card like Beacon of Unrest, for example).
The back face of a double-faced card is marked with a moon symbol, lacks a mana cost, and usually has a color indicator—a dot on its type line—that tells you what color it is. (Unlike most double-faced cards, Chalice of Death does not have a color indicator, because its back face is colorless.) The two faces of a double-faced card are often the same color, but not always. The back face's characteristics matter only if the card is on the battlefield and its back face is showing. Otherwise, only the front face's characteristics count. (For example, the preview card above has a converted mana cost of 3—except when it's on the battlefield and Chalice of Death is face up, in which case its converted mana cost is zero.)
Each double-faced card has at least one ability that causes it to transform. To transform a double-faced card, you turn it over so that its other face is showing.
Putting double-faced cards in your deck
To put a double-faced card into your deck, you have two options: You can put your entire deck in opaque card sleeves, as many players already do, or you can use the checklist card provided in many Dark Ascension packs. If you're using checklist cards to represent any of the double-faced cards in your deck, you must use checklist cards to represent all of them.
If you're using sleeves, it's pretty straightforward. You'll want to put the double-faced card in the sleeve with its front face showing, and take it out of the sleeve when it transforms. (Putting it back in is optional, at least until it leaves the battlefield.)
The checklist card has a regular Magic back. The Dark Ascension checklist card looks like this:
To use the checklist card, set your double-faced card aside and make a mark on each checklist card next to the name of the double-faced card it represents. (Be sure to use a writing implement that won't be visible through the back of the checklist card, and to mark only one double-faced card name on each checklist card.)
You'll use the checklist card when the card is in your library, in your hand, or exiled face down, and the double-faced card when the card is on the stack, on the battlefield, in the graveyard, or exiled face up.
After a double-faced card transforms, it's still the same card, so any Auras, counters, or other effects stay right where they are (unless the double-faced card's characteristics have changed such that an Aura can no longer legally enchant it).
Some double-faced cards can transform back and forth between their two sides; others, like Chalice of Life / Chalice of Death, transform in only one direction under normal circumstances. The word "transform" applies no matter which side is currently showing; cards never "un-transform."
Those are the basics. If you still have questions about how double-faced cards work, check out the Double-Faced Card Rules Page!
The Innistrad ability word morbid makes its return in Dark Ascension.
The morbid ability word indicates an ability that checks whether a creature died this turn.
Hunger of the Howlpack puts three +1/+1 counters on the target creature if a creature died at any point in the same turn prior to Hunger of the Howlpack resolving. If no creatures have died, it only puts one +1/+1 counter on. It doesn't matter if a creature dies later in the turn; the ability only checks as the spell resolves. If a creature dies after you cast Hunger of the Howlpack, but before it resolves, it will put three +1/+1 counters on the target creature.
Other morbid abilities may be triggered abilities, activated abilities, or abilities that change what an instant or sorcery spell does.
The flashback mechanic returns in Dark Ascension. Flashback appears only on instants and sorceries.
You can cast a spell with flashback from your hand as normal. When it's in your graveyard, regardless of how it got there, you can cast it by paying its flashback cost instead of its mana cost. You can do this only at a time you could normally cast the card. Even if you cast Ray of Revelation for its flashback cost, it's still a white spell, not a green one.
If you cast a spell for its flashback cost, it's exiled as it leaves the stack.
A Curse is an Aura that enchants a player and does something nasty to him or her.
There aren't any special rules for Curses—they follow all the normal rules for Auras that enchant players—but there are some cards in Innistrad block, like Curse of Thirst, that refer to the Curse subtype. Note that Curses have enchant player, not enchant opponent, so you can enchant yourself with a Curse if you want to.