That's not how Blocks work, as I recall. You roll defense if a block is bypassed, yes, but you take the larger of the two. If you have a block of 8, and your defense roll is 0, then you go with the 8 as defense.
From the section on wards:
If the attack surpasses the block strength of the ward, then the ward is breached; apply whatever shifts get through to the target just like bypassing a block (page 210).
So a spell with 36 steps hitting a 8 Ward would mean applying 28 steps to the target...
If it is considered an attack. Something has me thinking that if the symbolic link is strong enough that it spell bypasses the ward as opposed being treated as an attack going through it. Nothing in the ward section on that...
Not entirely true. As I understand it, a thaumaturgic attack is basically a big attack roll without an attack rating, not an 8-shift attack roll with a Weapon:28 rating. So yes, it can partially work--you'd take consequences to avoid being taken out just like with any other attack you couldn't dodge.
But it's not an attack. Attacks aren't listed as something that thaumaturgy can do. Thaumaturgy can do simple actions, maneuvers, and (most importantly of all) Contests and Conflicts. To quote from that section:
"The most complex spells outright kill people, leave them permanently insane, or transform them forever. These require enough shifts to bypass the resisting skill and all levels of consequence, including extreme. Victor Sells’ killing spell from the Storm Front casefile needs 32 shifts of complexity to do the job: enough to beat Harry’s Endurance, stress track, mild, moderate, severe, and extreme consequences, and an extra shift to take him out!"
That's not an attack. That's a magical effect that leave the target dead. There's no weapon rating, no targeting, only "You live" or "You die".
It might still take the guy out--it's just not a sure thing, if he's got consequences to soak it up.
If you have enough shifts to take someone out, then the death spell works. Or the shapeshifting one spell works. Or the "You think you're a chicken" spell spell works.
If you don't, then the spell fails.
Richard