Handling Water and Mortal Magic

[rientelfon]

Hey everyone,

I am not sure if anyone has ran across this situation or not, but in the books I recall Harry mentioning the effects of water on a mortal spell caster. I have yet to see any examples of this rule in place within the books that addresses this particular issue. How do you handle this? Would you treat the amount of water or the presence of water as a block against the caster? Or do you use it as a compel?

Thanks in advance! 

[Nepene]

But other things serve as thresholds as well.
In the broadest sense, the term “threshold”
may be given to any metaphysical barrier that
impedes or blocks supernatural power from
passing from point A to point B. A signifcant
source of running water is a prime example, as
it “shorts out” magical energies that try to cross
over or through it.

Most thresholds or other things that ground
out magical energy (like a source of running
water) have a base strength of Fair (+2).
Most public places or places used primarily
for the conducting of business have a strength
of Mediocre (+0). Sanctified or consecrated
grounds (such as places of worship) are an
exception to this, carrying a base threshold
strength of Good (+3) even if they are used by
the public, because of the energies of faith that
are directed into them.
From these guidelines, you can further
modify the strength of the threshold depending
on the circumstances of the location in question. Running the Game has suggestions about
modifying difculties (page 311); basically, every
mitigating or contributing circumstance should
add or subtract 2 from this base total.

So basically, make water a +2 threshold, with +2 for each additional factor, like it being a heavy stream, it being flood season, whatever.

Compels are also good and solve many problems. But everything can be compel'd. If you want your wizard to not have magic, you can compel them to not be able to cast while in a river they could otherwise overcome.

[potestas]

i pretty much just ignore it, never really made sense to me anyway

[Taran]

There's been a few examples in the books, including the frog Demon, and one of the fights on Lake Michigan.

Having a Threshold is an excellent way of doing it.  An aspect, as you suggested, would work as well.

It really depends whether you want the challenge to have a more mechanical effect (the threshold) or a more of a story effect (aspect).

Use both if you want.