4/11/2017 - Okay, today's idea is weird. Real weird. Buckle in, kiddos.
This actually started as an idea for a pre-extant game, but then I thought of aftermath and meld, and realized it could be a Magic mechanic. What if you had a split card where the left half is always playable, and the right half represents half a card, so that if you play two of these things together, you get to put those two halves together and win a bonus card?
I was originally thinking all the parts would be sorceries or instants, but to make meld modular (which is clearly more fun), you kind of need a creature because of the way abilities stack—both in terms of gameplay and visual presentation on the card. That has the side-effect that the other halves of the cards will be sitting on the board, book-casing your creature. We could try to ignore them, of course, but that's pretty ugly. (And ostensibly verboten for sorceries and instants.)
What if instead of the primary half of each splitmeld card being a sorcery/instant, they were something that belongs on the battlefield? If they were lands or creatures, you could never tap your three permanents independently. But they could be non-tapping artifacts or just regular everyday enchantments.
Imagine the right side of this card is just the top half of a creature:
And imagine the right side of this card is just the bottom half:
If at any time you control both Lunging and Hunting, their two loose halves combine and you get a 6/6 Rager at no additional cost. You still have Lunging and Hunting, so assuming you have no other permanents, you've got a 6/6 with haste, trample, 2 points of first-first-strike, and one free fight.
(We could also arrange the cards so the split is vertical, the first half being simply very narrow, or sideways, and the meld half being the left- or right-half of a complete creature card.)
Add just one more top- and one more bottom-half and you've got four possible combinations.
All of these cards are enchantment creatures at all times, except when you have an unmelded enchantment on the battlefield. That helps with things like delirium and type-specific tutor effects, but it also makes these creatures vulnerable not just to Murder effects, but also Naturalize effects, since taking out either enchantment would end the creature.
What does happen when you Murder a melded creature? We could follow the existing meld rule and say both cards go to the graveyard, taking the enchantments with them. We could also just split the cards up, saying that creature is destroyed, but the enchantments remain. As tempting as that is, things get a lot more complicated with other kinds of creature removal. If the creature changes zones, shouldn't the cardboard its own follow? We could try and hack it and see the creature is treated like a token for purposes of state changes, but now things are wicked complicated.
Before I came to that conclusion, the question prompted me to think about how the two halves of such a creature would meld. Above, I was kind of hand-waving that it happened automatically as soon as you control both a top-half and a bottom-half, but it could be an activated effect, or a trigger with a cost/condition.
This is a swingy mechanic: You might get three cards for two, but you might never get a valid pairing. Or you might get your free creature, only to lose the whole shebang to a single Demystify. Like most of the Innistrad melds, we want a good portion of our splitmeld effects to either help us assemble our combos, or help protect them once we get them.
Seeing as how our enchantments are inclined to buff our creatures anyhow, what if they were auras instead of global effects?
Maybe you could cast one on a creature this turn, and the other next turn, and they would both slough off that creature and make a new creature, enchanting it automatically. Deadly Tougher Nightharpy would form a Vampire Nighthawk, for instance.
Finally, I have to note that this final solution isn't that much fundamentally different from the existing meld tech. If we just make these double-faced cards instead of split cards, they can flip to the creature side when you pair them up. You can even keep the back-side an enchantment creature with both abilities of the source cards, if you so choose—though that constraint falls away with our more consistent solution. Meld doesn't currently allow for mix-and-match combinations, but in fairness, I totally hand-waved significant art issues with splitmeld. Ah well. It was a fun exploration.