The defense crystal in Trun Coat that Molly uses could be modeled as a potion.
Assuming Harry has a base potion strength of 5 in Turn Coat and he "sells" duration down two steps on the wards, from "a day" down to "a few hours", then that would give him a power 7 ward in a can that would last a few hours. If he spends his other potion slot in making the crystal more powerful, and invokes an aspect, that would give him power 10. So he could have something like a force 5 ward with a power 3, area 1 land mine effect, for example. Possibly not as powerful as the whole thing was implied to be in the book, but still something useful to have.
Are there any instances of Mister coming and going out of the window, for example? I know that Harry usually opens the door and, we can assume, takes down the wards, to let him in. I sorta remember Mister coming into or out of the window at least once though. Does anyone remember where (or if) this occurs in the books?
Does anyone have an opinion on how casting magic out through the wards works?
Or how they think the zombie assault in Dead Beat would be modeled in the rules?
There are a few possibilities:
1
Each zombie attack was sufficient in power to breach the wards.
The "land mine" was going off each time the wards were breached
The wards were falling quickly because there were enough zombies around to beat down the wards, despite the casualties
The 'enhanced protection mode' version of the wards would have been too powerful for the zombies to breach with an attack, so the zombies would have been unable to beat their way through the wards.
So model 1:
Harry's wards were somewhere between force 6 and 8. The zombies, with inhuman strength and good fists, can, with a good fists roll, hit hard enough to cause a breach in the wards.
This sets off the landmine. Since the landmine can blast a zombie in one go, it's somewhere between a power 7 and maybe power 13 effect.
The enhanced protection mode would raise the ward power by around 4-6 points, meaning that the zombies would no longer be able to cause a breach in the wards.
So it would take between 6 to 8 ward breaches to bring the wards down, which would cause an equal number of land mine detonations.
2
Each zombie attack was not sufficient to cause a breach in the wards.
However, the "land mine" was set to go off every time the wards were hit "hard" and each zombie attack was hard enough to set off the land mine
Each time the land mine went off, it drew power out of the wards and that's why the wards would fail quickly
The enhanced protection mode of the wards would have provided enough extra power to them that the land mine would have had enough shots to bury the stairwell in a pile of dead zombies, so the zombies would not have been able to drain the wards by setting off the landmine barring the most exception circumstances.
Model 2:
Harry's wards are something like power 8+
The land mine goes off when they are hit by a power 5+ attack
The land mine is around power 7 to 13
However, each time the land mine goes off, the wards are drained.
(Maybe the wards are moved down in duration 1 shift on the chart every time the land mine went off? So if the base duration of Harry's wards was one month, it would take around 10 land mine detonations and a few minutes for the wards to go down.)
I'm not sure exactly how the enhanced protection mode in this model would help. But if it provides another 6-8 shifts of power, that would be another 6-8 land mine detonations. And 15-20 bodies is probably more that enough to pack the stairwell full.