Blocking the Defense

[Lavecki121]

The discipline roll is all offensive. It's just that if you mess that up you could easily hit yourself with the attack (internal backlash) or an ally (fallout). You are allowed to put blocks on this as per normal. I dont think that if they beat the block it reduces the roll (7 shift block 8 shift roll) but i could be wrong. EX:

If I put up a 5 shift block and the caster wants to cast a 5 shift attack.

They roll a 7, without the block they succeed and they do blow through the block but is it a total roll of 2 (7-5) thus inflicting 3 points of fallout/backlash or is it just that they blew through it and it deals as normal but with 2 points from targeting with the weapon 5?

This is my confusion, hopefully i worded this ok.

[Tedronai]

You do not get to apply both the block AND the normal target number.  Compare only to the higher of the two.
If the block is higher than the normal target number and the roll, whatever it is, beats the block value, then it is treated as if it had beat the normal target number by whatever margin by which it beat the block value for the purpose of calculating additional effects.  Control has no additional effects, so it's just a matter of pass/fail.  If the Control roll beats the block (assumign the block is higher than the Power), then the Control roll also beats the Power.

[UmbraLux]

If the attack value equals the block, the target takes stress equal to the weapon value.  So a power 5 attack with 7 control / targeting will inflict no stress if the block is 8+, 5 stress if the block is 7, and 5+(7-block) stress if the block is less than the control / targeting roll.  If the normal defense roll is higher than the block, use it instead.

Block or not, the control roll needs to be at least equal to the spell's power, 5 in this case.  Else you head to the backlash / fallout rules. 

[Taran]

The text of the Grapple section implies otherwise. Harry muses that under a grapple, him casting even a low power spell would be a difficult to control as a high powered one, implying that a grapple would, indeed, block his control roll.

YS 212

"The
thug’s Might is Good (+3), and he rolls a +2
on the dice for a Superb (+5) grapple. Harry
is held. He decides that casting a spell while
grappled is too chancy, since the Superb grapple
blocks his target roll to control even a minor
evocation. Harry instead opts for the straightforward
approach: headbutting the thug. He
rolls Fists for this attack, but the outcome is less
than Superb. Harry remains held."

The bolded part is not mine.  It's actually bolded in YS.

Edit:  In the margins, p.212

"So even if I
was trying to
cast a, uh, Fair
spell, it’d be
as difficult as
trying to cast
a Superb one
when the block’s
that big?"

[Lavecki121]

That implies that the block would take away from the control/targeting

Ex: a 2 shift block would reduce the targeting by 2.

[Taran]

I think it implies that you take whichever is higher.

So a 5 shift block on a Power 3 spell would require a 5 shift control roll as opposed to a 3 shift control roll.

What is not clear is what happens if you fail that control roll.  What if I roll a 4 shift control, against 5 shift block on a power 3 spell?

How I've always done it is the spell just fails.  But Does the spell just fail?  When you normally fail a control roll, the spell still goes off but with unwanted consequences.  So, with a block setting the new difficulty, does the spell succeed but with fallout/backlash?  Would you take backlash equal to the difference you failed up to the power of the spell?

So if you rolled a 2 to control a power 3 spell, but there was a 5 shift block, you'd take 3 points of backlash/fallout.

[UmbraLux]

That implies that the block would take away from the control...

More specifically, a grapple will.  Grapples block "all actions" (YS211) while standard blocks may only be used against a "specific type of action" for which you need "an appropriate skill" (YS210). 

If you can justify a skill as appropriate you could presumably block control specifically...but I can't really think of any that fit by default.

[Mr. Death]

I think it implies that you take whichever is higher.

So a 5 shift block on a Power 3 spell would require a 5 shift control roll as opposed to a 3 shift control roll.

What is not clear is what happens if you fail that control roll.  What if I roll a 4 shift control, against 5 shift block on a power 3 spell?

How I've always done it is the spell just fails.  But Does the spell just fail?  When you normally fail a control roll, the spell still goes off but with unwanted consequences.  So, with a block setting the new difficulty, does the spell succeed but with fallout/backlash?  Would you take backlash equal to the difference you failed up to the power of the spell?

So if you rolled a 2 to control a power 3 spell, but there was a 5 shift block, you'd take 3 points of backlash/fallout.

Yeah, I'd say it has to be either backlash or fallout in that case. Narratively speaking, though, the fallout on a roll like that might mean that the wizard controls the power, but can't hit his target (say, being grappled from behind, Harry lets loose with Fuego, but can't aim it, so it ends up going into one of the trees and setting that on fire).

[Mrmdubois]

I think it implies that you take whichever is higher.

So a 5 shift block on a Power 3 spell would require a 5 shift control roll as opposed to a 3 shift control roll.

What is not clear is what happens if you fail that control roll.  What if I roll a 4 shift control, against 5 shift block on a power 3 spell?

How I've always done it is the spell just fails.  But Does the spell just fail?  When you normally fail a control roll, the spell still goes off but with unwanted consequences.  So, with a block setting the new difficulty, does the spell succeed but with fallout/backlash?  Would you take backlash equal to the difference you failed up to the power of the spell?

So if you rolled a 2 to control a power 3 spell, but there was a 5 shift block, you'd take 3 points of backlash/fallout.

I think yes.  Like the time Harry got grabbed by MacFinn and got magical backlash breaking out of it.

[Lavecki121]

I think yes.  Like the time Harry got grabbed by MacFinn and got magical backlash breaking out of it.

Was just about to mention that