[Unahim]

Just to be completely sure here... Since the only limit on Sustaining Foci seems to be the Force of the spell cast, and in many cases Force only acts as the limit on the spell, it's totally legit to grab a Force 1 Sustaining Focus, cast something like Increased Reflexes at Force 1, use Edge, and put it into the Focus with however many hits you got, right?

I understand the drain may end up being Physical if the roll goes exceptionally high.

[Michael Chandra]

Has been confirmed as legal right now for both Edge and Reagents.

Note that it won't work with Increase [Attribute].

[Unahim]

Yeah, I suspected as much. Thanks!

[Shinobi Killfist]

Has been confirmed as legal right now for both Edge and Reagents.

Note that it won't work with Increase [Attribute].

That depends on the attribute.  There is a good chance a mage will built on c or D in attributes and assuming they give themselves decent stats in the drain stats expect a collection of 1s and 2s. 1 reaction now become 5 real quick. 

As a side note to the OP, I think the real person to ask is your GM assuming that is not you. There are a lot of things in most games that are rules legal, but are clearly rules manipulation at a level a DM might not be comfortable. I'd never allow it in my games as it becomes yet another things I have to micro manage to balance and the mage character already will have me doing more of that than any other archetype. . 

[Michael Chandra]

Correct, if you got low attributes you can boost them quite nicely cheap. It also means that after a mana barrier you are at risk of instant-dying. But while you can cast Increase Reflexes at Force 1 with reagents, it won't work for higher attributes, so you can't go raise an attribute from 6 to 10.

But yes, taking 4 stats on 1 and raising those with 4 Sustaining Foci Force 1 and reagents to 5, adding Increase Reflexes and Armor on top, means you can spend <500 nuyen in reagents to heavily boost yourself while not getting hit by Focus Addiction. It is also the point where you'll run into mana barriers quite often. And honestly if a player showed up at the table with more than a single attribute at 1, I'd disqualify the character.

Still, it's a nice but costly way for mages to avoid Focus Addiction and they risk being dispelled easily or getting hit by barriers.

[Shinobi Killfist]

Under point buy I might have a problem with multiple stats at 1, but E attributes should be viable and 12 spread among 8 stats will most likely mean more than 1 1.  Hell even D with its 14 in stats can be bad, lets go

A mage, B skills, C resources(now you can get focuses), d attributes, e human. 

Bod 2
Str 2
Agil 2
Reac 2
Cha 2
Log 4
In   2t
Will  5

Sure no multiple ones but

If they min/maxed just a smidge more and went 6 logic, 5 will 2 of hose 2s become 1, if they wanted a 4 in intuition so they could be decent at assensing, 2 stats are down to one, they do both and 4 stats are at 1.  This isn't the player screwing with things, it is the priority system giving really bad numbers for lower priorities.  I mean sure he could have 2s in a bunch fo things but he is hitting his focus hard and will suck at a lot of other mage like things for no real gain in the 2 stats. 

[Michael Chandra]

True, if they go E or D in attributes I'd be fine with it. I'd STILL toss the occasional mana barrier their way, and the occasional background count means any skilltest involving a boosted stat would suffer from a -1 penalty. And going K.O. would mean losing up to 500 nuyen, so eh.

[Unahim]

I think it's not too bad in the grand scope of things. There's still plenty of reasons to want in-built stats rather than relying on a bunch of Foci.

[Michael Chandra]

Indeed. So I don't mind the trick, but I'd make them face the consequences every now and then. Definitely not someone I'd slap around with the rulebook, causing (STR+1)P with every hit.

[Unahim]

Indeed. So I don't mind the trick, but I'd make them face the consequences every now and then. Definitely not someone I'd slap around with the rulebook, causing (STR+1)P with every hit.

In SR4th I considered high-end Foci to be pretty sacrosanct since they were so hard to replace, but I think any GM would be justified to occasionally destroy/steal 1 of your Foci if you have 5 Force 1's active everywhere.

[Michael Chandra]

With Focus Addiction being a default rule and with Magic, not Magicx2, as limit it's about the only way to handle a buff-build. But yeah, there'd be consequences. And don't forget that Extended Masking in SR4 only let you mask your grade in things, the more active Foci you have the higher you'd need to Initiate to hide them.