Illusionary Mask and Ixidron aside, Magic has only known one kind of facedown creature. It costs three mana, is a 2/2, and is completely generic - no name, creature types, or other defining characteristics.
It also must have the ability morph and flip face up for a cost. We saw them first in Onslaught block, then Time Spiral block, and now again in Khans of Tarkir block. Only a few morphs have ever made a difference in Constructed, as starting as a Gray Ogre is quite the drawback, and they are often too mana intensive to be reasonable.
This is all about to change.
Fate Reforged is coming, and with it comes a new mechanic, Manifest. To manifest means to put the top card of your library into play face down as a creature that is similar to a morph creature in every way except for one: if the face-down card is a creature, you may turn it face-up for its mana cost. This means essentially any creature will have an unmorph cost, and if the manifested creature happens to be a morph creature, you can unmorph it for its morph cost as well.
Okay, so we have an ability that seems to essentially make 2/2 colorless creature tokens that may occasionally be able to turn face up into real creatures. How does this help us?
At first glance manifest seems fairly underwhelming. We already have a bunch of unplayable morphs if we want crappy 2/2s, why do we need more crappy 2/2s?
There are three big factors that make manifest creatures very interesting.
They Are Colorless
Anyone who has played with Ghostfire Blade and a number of morphs in Limited can tell you how powerful it is. Bonesplitter is a marginally playable Constructed card, and adding two to the butt makes it quite good. Yet because of the dearth of good artifact creatures in Standard, morphs alone were not enough to bring Ghostfire Blade to respectability. Now, that changes.
Manifest comes cheaper and more efficiently than morph, and this in turn means that Ghostfire Blade might be able to find a deck to slot into. Some of the manifest effects that have been spoiled so far are in the form of auras that create a creature to be attached to them, and using Ghostfire Blade to help buff the bonus already given by the aura, such as lifelink or double strike, seems quite powerful.
They Are Often Made by Non-Creature Spells
While there are only a six manifest cards spoiled so far, half of them are either sorceries or enchantments and function very much like creature token-making spells. While this seems somewhat trivial, in a lot of ways this plays right into what many decks are doing in Standard right now.
Non-creature spells trigger prowess effects on Monastery Swiftspear and Seeker of the Way, and also trigger the ubiquitous Jeskai Ascendancy. Aside from that, the sorceries go to the graveyard, and when the creature created by the aura goes to the yard, both the creature and the aura are added to the graveyard. This is big for delving as well, as we all know how powerful Treasure Cruise is.
These are subtle nuances, but looking at decks like Jeskai Tokens, we can see how they all add up.
They Make Morphs That Have Low Mana Costs Insane
This is the most volatile but probably the most powerful effect that manifest has. While there are not a lot of creatures in Standard that fit this category, the ones that do are very good.
Master of Pearls is an absolute beating in Limited, but five mana to flip is far too much to be reasonable in Constructed play, even if you can play him as a bear occasionally too. Well how about only two mana to flip? Master of Pearls doesn't really care how he turns face up, just that he does, and if you manage to manifest him you are getting a huge effect for only two mana. Worst-case scenario he is a Runeclaw Bear or you just play him fairly as a morph, and neither of those scenarios are downright awful.
The other extremely exciting manifest option is Hooded Hydra. Already a somewhat reasonable card, being able to flip him face up for only GG is pretty amazing. He provides a big body, insurance if he dies, and again, his worst cast scenario of simply casting or morphing him isn't that bad.
There are a few other options as well, as the other three creatures in Standard with morph triggers and mana costs lower than their morph costs are Kheru Spellsnatcher, Jeering Instigator, and Icefeather Aven. You are not getting that much of a discount in all of these cases, but it is still something to consider.
Lastly, you can get a bit crazy in older formats with cards like Phyrexian Dreadnought, but that's for another day.
Spoilers So Far
So we've seen what we can do with manifest cards so far, let's take a look at the ones that are spoiled!
Probably the most basic manifest card, as it is essentially a Runeclaw Bear. That doesn't seem too exciting until you realize the effect that it has. Like we said, it triggers prowess and Jeskai Ascendancy, fuels delve, and so on, while also giving your opponent pause and letting you perhaps hit a morph card. If there is a deck that wants to manifest heavily, this card will almost assuredly factor heavily into it.
Soul Summons is simple, but most importantly it's cheap, and that is often what gets a card played in Constructed. I would not be surprised if this card ends up filling a similar role to Raise the Alarm or Hordeling Outburst.
When Moonform enters the battlefield, it becomes an Aura with enchant creature. Manifest the top card of your library and attached Moonform to it. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Enchanted creature has flying and lifelink.
Moonform is pretty exciting, as for one additional mana we get a Soul Summons with huge upside. Instead of a Runeclaw Bear we get a mini Baneslayer Angel, and if it is a creature, you can unmorph. Having lifelink and flying stapled onto it is a huge bonus. Imagine unmorphing a Goblin Rabblemaster or Polukranos, World Eater enchanted with Moonform. Of course, hitting a good creature, especially one with an awesome unmorph ability like Hooded Hydra, is the best case scenario. Our worst case scenario of a 2/2 flying lifelinker for three mana isn't bad at all.
While it doesn't go to the graveyard for delve, Moonform works great with prowess, constellation, and even bumps up your devotion count by two! It is also perhaps the best Ghostfire Blade target in Standard, and I expect that card to skyrocket in playability.
Moonform is easily one of my favorite cards spoiled so far, and is an awesome design.
Rageform is the red version of Moonform, and while it's not as good, it still packs a major punch. Double strike is not an ability to be taken lightly, and even on something as simple as a Mantis Rider, Ashcloud Phoenix, or Stormbreath Dragon it ends the game in short order.
Just like Moonform, Rageform also works great with prowess, constellation, devotion, and Ghostfire Blade. The lack of evasion is somewhat troubling, as is the higher cost, but Rageform is still a pretty sweet card.
Our last card is interesting because while it doesn't get a lot of the bonuses we talked about most of this article, it is still an extremely powerful card. Whisperwood Elemental is much more Grave Titan than Raise the Alarm, and that's okay. While you can bolster his power with something like Trail of Mystery, he is so powerful by himself that he doesn't really need much help as far as deckbuilding is concerned. If you can flip the creatures you manifest of off him great, but you aren't going to be needing Ghostfire Blade anymore than you need Undead Warchief to go with your Grave Titan.
It's not going to be hard to land Whisperwood Elemental when your opponent is tapped out and get at least one 2/2 from him, and if he ever stays in play, the advantage you gain over the course of a few turns is going to be huge. Much like Sidisi, Brood Tyrant, sometimes an army of vanilla 2/2s just gets the job done. If you happen to be able to flip them for more value, that's a huge bonus.
Whisperwood Elemental also provides some nice protection from Wrath of God effects like End Hostilities and the new Crux of Fate, as he acts like a pseudo-Xanthid Necromancer and will leave you with a small crew of manifested 2/2s.
Whisperwood Elemental is extremely powerful, and while not really a great posterchild for the manifest mechanic (as he would be just as good if he made 2/2 tokens) it is certainly a nice bonus.
Manifest seems like a sweet mechanic, as it expands on the mind games and bluffing potential of morph without forcing you to pay three mana for a vanilla 2/2. Even with no morph cards in your deck and a smattering of creatures, is that manifested creature a Goblin Rabblemaster, Elvish Mystic, Stormbreath Dragon, or something else? This is a question you are going to have to ask yourself many times over the next year, so you better get used to it!