Why, if I may ask?
I dunno. From a fluff perspective, counterspelling is disrupting the magical energies of a spell, so you'd need a second or two - in game terms, an exchange - to identify what those energies are and how to disrupt them (the Lore assessment), then actually do it (the counterspell). Thus, one exchange for a countespell. If you'd held action and interrupted, it would make sense that you did the first part while the enemy spellslinger was drawing their power, and could do the second part quickly. In an ordinary exchange, though, there just isn't *time* to study analyse the energies of the fireball that's on its way to melt your face. You either get out of the way (defend with Athletics) or, if you're good, nullify it with an opposing force (reactive block with Water or Spirit or whatever).
From a mechanics perspective, I feel that allowing casters to simply disappear any spell effect makes counterspelling too powerful, and it makes magic duels/fights *boring*. A series of spells fizzling from existence in between the casters isn't as cool as opposing spell energies clashing in the space inbetween them, or characters frantically throwing themselves aside just in time to dodge a bolt of lightning. There are mechanical benefits to the wizard counterspelling, but I feel that if you're having a full-on magical duel there should be some environmental damage.
PS: Two houserules that might be appropriate here:
1. Let Wizards use reactive blocks, but only against evocations. A Wizard buff and a Wizard nerf, all at once. I like this because a) it enables cool stuff, b) it makes spell fights less rocket-launcher-tag-like, c) it makes defensive foci better, and d) it doesn't actually make Wizards stronger the way normal reactive blocks do.
In fact, I might go so far as to let an unsuccessful spell-block reduce the blocked spell's power. So a 10 shift attack blocked by a 7 shift spell only inflicts 6 stress instead of 13.
2. Only let one focus be used on each spell, with the understanding the the (Lore) cap on slot spending applies to the total bonuses of a focus. This lowers the spending cap on Evocation, reducing the viability of uber-evokers.
1. This was what I meant. I wouldn't normally allow this vs. straight physical attacks or ambushes - if you're being shot at or caught off guard, you can't concentrate enough to cast the necessary spell. I *might* allow reactive blocks vs. gunfire - but only with a stunt or expenditure of a Fate Point to invoke a requisite Aspect (like 'cool under pressure' or something)
2. Apparently this isn't RAW, but I'd never allow (or use) more than one Focus per spell. not sure what you mean about the Lore cap, though. Could you explain?
Good catch, Mr. Death....missed that myself. I now see alot of situations where a counterspell would be so much better if suddenly your gm decides to get creative with splash.
See my above point on the destructive effects of Magical duels. This is just my preference, but I'm sticking to it.
Maybe, but I can see advantages to counterspelling instead of blocking--a block might stop, say, a beam of fire from hitting you, but may end up being thrown into the wall or the rafters or something. A counterspell would presumably just make the spell stop happening, so there'd be no splash.
True, although I'd argue that, depending on the way the block is described, this might not happen. A straight harry-style Spirit shield is one thing, but using Water to create a column of water to quench the fire or merely altering its course away from you are all blocks, mechanically. I'd use both of these to make Scene Aspects, as GM - the first, 'Cloud of Steam', the second would set something on fire.
