Neutralize!

[Becq]

I don't see how any of this is workable by the RAW.

Blocks can only block actions, and I don't recall anything about suppressive blocks that aren't armour.

Am I forgetting something?

The following quotes are per YS252:

Blocks are usually set up as a defense against damage—particularly if the wizard is especially focused on combat. But not all wizards are, and in such cases a blocking spell can be used as something other than a shield—an evocation-based veil, for example, is often done as a block, but what it blocks isn’t damage, it’s perception

Note: establishes that blocks can be set up in self-defense against damage, or alternatively to inhibit "something" from occuring.

Hey Billy, would you use a “block” effect to hold a target in place, sorta like Elaine did to me in the SUMMER KNIGHT case?
Probably, yeah. The thing to remember with any “how would I” question is that there are probably multiple answers. You could model an entangle spell as a maneuver (the aspect used to slow you down), a block (against movement), or that special sub-type of a block, the grapple (page 211).

Note: Establishes that blocks can be placed "aggressively" on other people in addition to "defensively" on yourself or allies.

Optionally, instead of block strength, you can opt to have the effect work as Armor or as a zone border instead. If you choose the Armor effect, the armor rating is equal to half (rounded down) the shifts put into the spell. The advantage to doing this is that the Armor effect only ends when the spell duration ends—the armor survives a bypassing attack.

Note: Establishes that a block can either have a "block strength" or an "armor rating" or a "zone border".  Regardless of which mechanic is chosen, however, it's still a "block", and:

A Block Is a Block Is a Block

So the above is how I make the claim that a block spell could be designed to inhibit spellcasting (first quote) by foe (second quote) by means of the armor mechanic, subtracting shifts from the final result after success is established (third quote) and that the result would be a legitimate block, per RAW (fourth quote).

Oh, and look: quote 2 also explicitely establishes The Spell Which Shall Not Be Named...  :p

[Sanctaphrax]

Offensive blocks are totally kosher, as are blocks against movement or spellcasting or whatever.

But I don't think it's ever established that there's an armour equivalent for things that aren't attacks. In fact, you quote implies that there isn't by saying "bypassing attack".

It's important to remember that armour applies to stress, which is something non-attack actions don't have. It does nothing to the attack roll, it only affects the effect of that roll.

Hard to translate this to things which are all attack roll, with no separate effect.

That being said, it might not be a bad idea to try something.

PS: Magical grapples might be okay, if you had to follow the grapple rules to inflict them. The spell in question here gets to be cast without an Aspect invocation and without supplemental action penalties, because...because.

[InFerrumVeritas]

Offensive blocks are totally kosher, as are blocks against movement or spellcasting or whatever.

But I don't think it's ever established that there's an armour equivalent for things that aren't attacks. In fact, you quote implies that there isn't by saying "bypassing attack".

It's important to remember that armour applies to stress, which is something non-attack actions don't have. It does nothing to the attack roll, it only affects the effect of that roll.

Hard to translate this to things which are all attack roll, with no separate effect.

That being said, it might not be a bad idea to try something.

PS: Magical grapples might be okay, if you had to follow the grapple rules to inflict them. The spell in question here gets to be cast without an Aspect invocation and without supplemental action penalties, because...because.

We allow grapples, but you must use an action to make an action with it (the block remains in place, but if you want to maneuver or deal stress it's an action).  We have a "targeting" roll be the same as an aspect invocation (so the person being grappled gets two shots to avoid in the first round).  I know the second bit's a house rule, but it's easier that way.