Community

Incubating Plague
Instant

You get an emblem with "Whenever Incubating Plague is cast, counter it, then destroy target creature."


Surgery
Instant

You get an emblem with "Whenever Surgery is cast, counter it, then gain 7 life."
 

Channel
Instant

You get an emblem with "Whenever Channel is cast, counter it, then add to your mana pool."


Rally
Instant

You get an emblem with "Whenever Rally is cast, counter it, then target creature gets +2/+2 and haste."


Research
Instant

You get an emblem with "Whenever Research is cast, counter it, then scry 10."


Rapture
Instant

You get an emblem with "Whenever Rapture is cast, you win the game." 

Very nice :-)

And hell yeah, scry 10.

These have the potential to be hilarious

Rapture could get silly with Cast Through Time as the above person mentioned, but if you can do that, so worth it.
Show And Tell -> Omniscience -> Enter the Infinite -> Cast Through Time -> Rapture for best combo 2013. You heard it here first, folks.

Wow. Very interesting. I wonder if it would be worth raising the cost in order to ditch the "counter it" clause... I know you're trying to avoid letting the abilities stack, but I almost feel like that would be more fun.

Hm, these could also name other spells in their text. Like, "Whenever a player casts a spell named Rally or Research do x," if that makes sense. It would be an interesting synergy, although I'm not sure how players would feel about having such obvious deckbuilding instructions.

What if, to make it a bit crazier, you gave these all a supertype (like Arcane, but somthing else, we'll call their supertype Stack) and then you make the emblems read "Whenever you cast a Stack spell, you may counter it. If you do, [do whatever]."

You'd probably want to give them much more minor effects, but that way you have more choice (add another emblem OR counter it to use the existing emblems) and you don't need to run all of the exact same card, but instead just have a lot of Stack supertype cards, or whatever.

Maybe to avoid craziness issues you could word it like a replacement effect where only one emblem can be activated for one countered Stack spell (like how if you have two Totem Armor auras on a creature you only have to sac one to replace a destroy effect)