Wow. Awesome.

Thanks! I have a few of these, but I think they're not all executed quite as well.

Note that the toughness boost from Power won't help the creature out in combat much; flipping to Speed after damage is dealt may cause the damage it has to be suddenly lethal, and it's effectively just +3/+0 in that case.

Which side is supposed to be the unflipped one (i.e. if I want to transmute for this, does it take a 1 or a 2?)

I know. Originally, it flipped at end of turn, but I thought that was too wordy so I bit the bullet and changed it to flip on damage. The top side is the unflipped side.

Its a good idea to have unflip cards as auras, so you can hide the wrong half under the creature if you want.

I dont know what you'd intended, but can you cast either half or not? should it either (a) have both mana costs, so can be cast either way or (b) have no mana cost at all in the flipped state?

Yes, I'm not sure why the green half here has a mana cost. If you're intending to change the rules so that you can cast either half, you'll definitely need to spell out that's what you're doing. (And whether you intend to allow people to cast the flipped versions of the Kamigawa split cards with Fist of Suns and Jhoira of the Ghitu, or how to prevent it.)

As originally intended, yes, you could cast either half. I hadn't thought about the issues this raised with the original flip cards, however. I'm not sure whether or not Fist of Suns would be a problem-- can you cast Evermind with it? Jhoira... I don't know. I don't have perfect knowledge of the rules. This is probably too big of a question for me. Likely, I'll remove the cost from the flipped side. However, do you think it's acceptable still to flip from another color?

Every now and then we seem to stumble into a "the rules don't say you can do this", vs. a "the rules should say you can do this" argument. I lean towards the mentality that if the rules are in the way, the rules can be changed to accomidate the new idea. In this one specific example, I'd like to point to the fact that this style design flip card was mentioned in two separate Great Designer Searches, and both times, none of the judges bothered to cite the fact that you can't do this in normal Magic. It just wasn't important to them. Of course, this is very important to the rules team, who have no interest in changing the rules to suit your whims. Ah, well...

As far as I'm concerned, we'll see flip cards with two converted mana costs in the future. That may be the far-flung future, though, since it seems that flip cards may take 5-7 years to return, and they probably won't be doing this the first time they return. I'd still prefer to be a futurist, though. ;)

Hmm... good point. I was raising concerns that aren't really appropriate here. I think when designers submit this idea inside WotC (as I'm sure they do), the Rules Team probably do push back at them with this kind of concern; but it's a pretty minimal concern, and you're completely right that it's not the designer's job to worry about it.

Multiverse is somewhat agnostic between whether it's a site for just design, or for design-and-development. Rules problems are the kind of thing that developers need to worry about. However, I'd agree it was out of place for me to raise these concerns as soon as such a card was proposed.

I think I mentioned the Jhoira / Fist interactions because I'm a Johnny/Melvin, and I find it interesting that this is what the consequences of this rules change would be.

To answer the Evermind question: Originally Fist of the Suns and Isochron Scepter didn't let you cast Evermind. But in order to make Suspend work, Time Spiral changed the rules about nonexistent mana costs, which meant that it became possible to cast Evermind in these ways. It was an irrelevant enough change that they didn't care. Nor should you when proposing this similar change. It's not going to break extended if someone can pay for Dokai, Weaver of Life.

Of course, Erayo's Essence would more more annoying to cast consistently, though at or suspended at least it's not gamebreaking. I guess.

Now, of course, this would probably be a double-faced card.

Yeah, I know, right? So much for me being a futurist and predicting that future flip cards would end up having two separate mana costs somewhere down the line. It's very likely that we will never see a flip card again. ;)

Though, the design is still solid. In the future, when double-faced cards are obsoleted by holographic cards with memory wipes, it will still smash for 3.