Together with Hellbat, this card has a morph ability less because of how awesome it can become when flipped, but rather for the flexibility that it provides (and as bait to protect your other, more awesome morph creatures.)

Apparently, this also means this is effectively a 3/3 with ": ~ gains flying until end of turn." Pretty good. Changed Hellbat cost to make +0/+4 / +0/+6 harder.

I just noticed during the Siege Tank discussion that it's somewhat counterintuitive relative to the computer game that the Viking's ground mode is better in combat than its flying mode. I can't see a sensible fix, because the point in the SC unit is to be a good anti-flyer unit that can shoot badly on the ground if you really need it to. Perhaps a 3/3 flyer with "Prevent all damage ~ would deal to players" that can turn into a face-down 2/2 ground creature?

Yep I know, that's its role in the game, but in MTG the fact remains that flying > not flying. This is ok I guess. I can sacrifice a bit of intuitiveness for SC flavor. What about this?

Viking
Artifact Creature - Terran Ship [c]
Flying
Morph
When ~ attacks and isn't blocked, turn it face down.
3/3

I prefer the old version by a small margin, because 1) I'm worried of how intuitive this might be. 2) I like the player to have control over hellbats and viking transformation, and 3) A bit easier to think "do I want a 3/3 ground guy or a 2/2 flyer?"

Also note that the previous version is basically a 3/3 with : ~ gains flying until end of turn.

I think the current solution is very elegant and that elegance is likely worth the loss of parallel with the game.

Previously:

Viking
Artifact Creature - Terran [c]
Morph
­, Turn Viking face down: Viking gains flying until end of turn.
3/3

• Switch keyword introduced, variant of morph which allows turning the creature face down. Still don't know whether we should change face down cost from to .
• For Viking and Hellbat, solves a lot of rules questions on timing and how exactly the old ability works.
• Simplifies a lot of text for Viking, Siege Tank, etc.
  3/3

Switch is a very fiddly mechanic that isn't actually doing all the things you want it to do. Right now, seems like you want a mechanic that lets you change between two modes (like a SC viking). This card actually doesn't really do that, and leads to massive blowouts on curve. 3 mana 3/4 is honestly pretty big, which is what this card plays out as. 3 mana is so cheap to flip, that you cannot really ever block a face down card early without the risk of just losing out. Take a look at the Khans of tarkir morphs compared to the Time Spiral ones. The ones in TSP tended to be pretty vicious, while khans morphs are considered excellent. This wouldn't normally be a problem, gameplay would show its better to up the switch cost....except for the fact that the switch cost is now also an activated ability later on. Herein lies the problems with this mechanic. You cannot balance the activated ability cost against the unmorph body without making the card look unplayable. My suggestion is simply do away with Switch and make them Double Faced cards. Imagine a card that is (3)(W) 3/3, has (1)(W)(W): Transform into a 2/2 flyer, only activate this ability as a sorcery (double swapping for more damage might seem fun but its not when you invalidate flyers that you payed far more to cast). Now the card is very clear. It is clearly either a 3/3 ground pounder or 2/2 flyer. Both are fairly average on rate, which by split card rules the card punches above cost. Same things go for all the other switch cards. No need to place so much of the complexity budget into hard to grok morph when a DFC will suffice. If you hate DFCs, there is always the "this card gains flying and has base power and toughness 2/2 until end of turn" technology. Like the set btw.

• The flip down trigger shouldn't be an activated ability, it should be a special action like morph. I had a brainfart and the reminder text is wrong and misleading.

• Switch fulfills two things - allows morph-bluffing, and gives you some incentive to flip a face-up card back down. From a gameplay perspective, switch cards are mixed between those that will punish you if you block them ( Siege Tank, Viking... ) versus those that punish you if you DON'T block them ( Spider Mine, Ghost, Terran Banshee because you want to trade with it.)

• DFCs were our first mechanic for Terran, but we play these with physical cards and don't really like the inelegance. DFCs don't also capture the bluffing aspect of cloaking units.

• We're aware that the power level of the switch cards are very pushed (see Wraith, which gives red a 3-power flyer for 3, plus other benefits). It is jarring in a normal set, but here it's needed to keep the balance between the three races relatively stable. Red and white are so craptacular at card advantage that we had to push their power levels up in some way.

So to sum yeah we're aware of the design wonkiness of these things, but in practice it plays better than it looks, and in the grand scheme of things the decks are still balanced. :) Definitely would control the power outside this set though.