Ok, so here is the question.
Once a sustatining foci is activated do you then cast the spell?
Or do you cast a spell into a Foci and then Activate the Spell in the foci?
This is the debate.
Ill give an example.



Mage Cast Armor lets say into a force 5 foci
Does he cast it when it wants to activate the foci or does he cast it and it sits shall we say in the Foci
For instance I am about to go into battle but I dont feel like getting prying eyes at the stuff'er Shack. So I "precast" armor 5 into my level 5 foci so I only need turn on the foci to activate the spell within or do I need to Dragon Ball Z it and cast like Armor/Improved Reflexes ect ect ect into them when I want them?
The issue is that right now im forced to cast into the foci when I want to use the spell so if we get jumped im good for about one spell per combat turn, which sucks.

As far as I knew, the focus has to be active first. Then the magician casts the spell through the focus at the moment he needs it and then the focus sustains the spell for the magician (which sounds like what you're being required to do now). As for "precast" stuff , IIRC there's metamagic that actually does that (or something similar). ATM I'm not really interested in doing research into SR4a & SM for details, so I'm only going off of memory.

Now if your combats are only lasting for a turn, I wouldn't complain too much. Either your party's quite good, or the GM isn't being challenging enough.

The focus needs to be active first (simple action). You cast the spell as normal, as and when you want it to take effect, and must decide there and then whether to sustain it with the focus or not.

When a sustaining focus is deactivated, does the spell it's sustaining get "lost", so that when the focus is activated again, the spell isn't being sustained? I mean, of course that makes sense, and is something I would rule in a game, but I don't see any specific rule on it...

It isn't stated explicitly, but I'd say your common sense approach is quite right. Otherwise sustaining foci become a much more useful alternative to the Quickening metamagic.

I wasn't able to find a clear SR4 rule on this either. There are these 2 rules on SR4A pg 199:

A - If the focus is snatched away or dropped, it immediately deactivates and all benefits are lost until it is recovered and reactivated
B - If a spell sustained by a focus is disrupted, it ends; the focus is still bound to its master and she may use it to sustain
another spell.

Line A can be interpreted as, if you reactivated any previously deactivated focus (including a sustaining focus), you immediately regain all benefits (does all benefits include whatever spell it was sustaining?).

Line B hinges on what constitutes as disrupted. Bringing it through a ward is one. But does intentionally deactivating it before going through the ward constitute as disrupting it?

Re-casting a new spell through the focus is normally of little consequence unless you are doing things like re-casting Increase Reflexes into a rating 1 focus and using edge to bump up the success



Argument

The SR4 sustaining focus seems to work differently from the sustaining focus/spell locks in SR1 through SR3.

In the older editions, the sustaining focus can only ever sustain 1 spell that's "locked" into it. Once that spell is decided/cast into the focus, you can't change it, including the number of successes rolled in the initial sorcery test (at least without spending karma to re-bond the entire focus). However, you can activate/deactivate it at will and the spell will activate/deactivate respectively (with the same number of success).

SR4 allows you to change whatever spell it helps you to sustain by simply casting another spell through the sustaining focus. This is obviously superior since you can re-cast (augmented with edge of course) a spell into it until you are happy with the number of successes. So a good way to balance it would be to have it lose whatever spell when deactivated.


Counter-Argument against myself

You can simply get around this by creating a custom sustaining focus as per Street Magic. One that would work like a normal SR4 sustaining focus but do not lose the spell after being deactivated/reactivated.

That's what it seems like to me. If the focus is deactivated, it is no longer sustaining the spell. If the spell is not being sustained, it expires. All the sustaining focus does is to take over the requirement that the magician concentrate on the spell to sustain.

What that means is if you want to "precast" your Armor spell (or your Increase Reflexes spell, which is quite popular), your sustaining focus has to stay "on" for as long as you want the spell to stay active. If you turn it off, it's no longer sustaining the spell. It's not unheard of for a mage to cast Increase Reflexes into a Health spell sustaining focus at the beginning of a mission and leave it on throughout...I've had people sit down at a Missions table and do that right off. Being able to turn them on/off and keep the spell as initially cast was how the old Spell Locks worked, but I don't see anything to indicate that here.

Note also that each category of spell (Combat, Detection, Health, Illusion, Manipulation) requires its own sustaining focus (or spellcasting focus or counterspelling focus), so one made for Health spells does nothing for Combat spells (SR4A, p 199, bottom of first column).

I have to second Fringe's interpretation. You can cast the spell whenever you want (precast). Heck, you could even cast it and keep it up for weeks via a focus if you wanted, but it would always be 'on', no switch for if the spell is active or not. Spells have two states, active, and not existing (not counting the metamagic that lets you set up spells that activate under certain conditions)

Still, most spells aren't noticeable by mundanes, so it really doesn't seem like a serious issue if your improved reflexes are on 24/7. It might be a minor annoyance while waiting for stuff or driving a car or something as time seems to go by more slowly, but that's a small price to pay for always being prepared as a runner.

Or a major annoyance once you develop a severe case of focus addiction for leaving a focus on for weeks on end.

Nah. That could never happen...

Ehh, I don't know that leaving one on all the time is going to cause addiction. From reading it is seems much more to deal with relying on them heavily as opposed to them simply being on. It's kind of like having the internet doesn't give you media junkie, it's actually going to all those sites that gives it to you.

Perhaps. But, if you are always using one spell channeled through a sustaining focus, I might require an addiction test with scaling target numbers every few weeks. Days is the spell(s) you are relying on are heavily used (example, Increase Initiative when you are getting into a fight every few hours, or Shape (Clay) as a custom pottery maker.)

The rules on focus addiction are quite clear: As long as the total force of all foci activated at one time does not exceed twice your magic, you don't risk focus addiction.

And quite frankly, trying to force focus addiction on a character who keeps a F3-4 focus active 24/7 is incredibly lame.

Indeed...

I was victim of a nasty GM move once. My mage had a F5 Weapon Focus and a force 5 Manipulation Sustaining Focus. Now after a big run, we're in for some big non-cash rewards and the GM gives me a F5 Health Sustaining focus. I had Magic 7, not 8!

Just don't activate them all at once...
Or cash one in for a lesser Focus...
Lot of ways to avoid Focus Addiction.

Note that you still get normal resistance tests vs addiction, and addiction only applies if all of your foci are active at the same time.

Or, just, you know, don't bond the new focus. The GM can't force you to spend karma.

Indeed...