Playing around with countering in white. This is meant to counter stuff like Fireball, Shock, Drain Life, a Sign in Blood targeted at you, etc.

A lot of the time, I'd rather pack a Reverse Damage. Seems to do a better job than Cancelling it. I admit, though, there are a few times when the problem isn't the damage, but what's riding with it.

It's rather got the same problem as Self Sacrifice: it needs to look forward in time to see what would happen when the spell resolves. E.g. if I have a Pariah on a creature, would a Lava Spike deal damage to me? No, it wouldn't, because the damage is going to be redirected. If I have a planeswalker that my opponent is trying to kill, would a Lava Spike deal damage to me? The opponent doesn't choose until Lava Spike's resolution whether it would deal damage to me... If an opponent casts Mind Bomb, would that spell deal damage to me? Depends what I do on resolution...

All these kind of cards that want to do something to a spell or ability before it resolves but based on what it will do when it resolves have this kind of problem, which is why Wizards avoid printing them.

For an example of this problem, see Unyaro Griffin. In its Mirage printing, it said "Counter target red spell that assigns damage to you or a creature you control". The problem was, the game doesn't know where the damage is going to be assigned when the spell resolves. There could be any number of replacement effects applicable, with any number of players to make choices during resolution... When the card was reprinted in Sixth Edition, they changed it to say "Counter target red instant or sorcery spell" because it's just not possible to restrict targeting based on what might or might not happen when the spell resolves.

That said, I think there definitely is room for countering in white. This is pretty similar to Rebuff the Wicked, and I think that's very much within white's pie; it's similar to Gilded Light.

White can prevent damage to creatures to; so "Target spell that causes damage" seems not unreasonable.

Trying a different wording, this should get around things like Pariah etc as it doesn't care where the damage ends up, only that the spell deals damage and targets you.
Thanks for the link to Rebuff the Wicked Alex, it gave me a better idea of how to word this.
I think the wording may need clearing up this way but I am stumped for how to word it properly at the moment.

Even with this wording, can it counter Skullscorch?

@Vitenka: But does Mind Bomb cause damage? Does Goblin War Strike with zero Goblins, or Rupture sacrificing an Ornithopter? Does Lava Spike if a CoP: Red activation has resolved?, or if I've got Pariah on Cho-Manno, Revolutionary?

­Mind Bomb and Rupture don't target Goblin War Strike specifically says 'deals damage' and 'target player' as does Lava Spike
The wording I'm trying to get doesn't care about resolution, it checks when the spell it wants to counter goes on the stack...does that spell target me? yes or no...if no can't counter...if yes, does it deal damage...if no, can't counter...if yes then lets stop that nasty thing.

I would say that this doesn't counter Skullscorch as it targets to discard cards. The damage is a replacement effect that the target gets to choose on resolution