[Nebular]

I'm wondering how exactly Stacked Foci work as far as binding karma costs go (Street Magic p84). Let's say a character has acquired a Spellcasting Focus Force 3, Sustaining Focus Force 2, and the formula to create a stacked Focus. The character hasn't bound any of his Foci yet. Does a character first need to bind the Foci (12 Karma for the Spellcasting + 4 for the Sustaining), create the stacked Focus, then bind the newly-created stacked Focus (another 16 Karma for a total of 32 Karma), or do they simply create and bind the stacked Focus (just 16 Karma)?

Once they're bound, it sounds like you both the Spellcasting and Sustaining Foci would be treated as being Force 5. Is that correct? Seems pretty potent.

[Mirikon]

A stacked focus isn't just slapping two foci together. The formula for a stacked focus would make an entirely new focus, so he'd have the two foci he had before, plus the new stacked focus.

[Nebular]

Oh, I didn't realise it created an entirely new focus; I thought it just created some sort of magic link between the two (or however many). So in the example, you'd really have 3 Foci: Spellcasting 3, Sustaining 2, and Spellcasting 5/Sustaining 5, correct?. Would the karma cost for binding that stacked focus then be 16 Karma (12 karma for Spellcasting 3 + 4 karma for Sustaining 2), or do you calculate the cost as Force 5 for each (20 karma for Spellcasting 5 + 10 karma for Sustaining 5)?

[Mirikon]

A Spellcasting 5/Sustaining 5 focus would have an effective force of 10 for purposes of dealing with background count and the like. It would take 30 karma to bind (5*4 for the Spellcasting, 5*2 for the Sustaining).

Now if you wanted a Spellcasting 3/Sustaining 2 focus, that would be an effective Force 5, and would take 16 Karma to bind.

The main benefits of having a Stacked focus instead of two or more individual foci is that you can only have up to your Magic in number of foci bound. The maximum force of all your bound foci is still Magic x 5. The cost to make the stacked focus will likely be the same as buying both the individual foci. Also, since background counts affect the strength of foci, the higher effective force of the stacked foci mean they hold up to higher background counts.

[Nebular]

Ah, ok. So it seems that I misunderstood the part where it talked about their combined force. For some reason I was thinking that if you stacked a Spellcasting 3 Focus and a Sustaining 2 Focus, each would increase their effective force (which is where I got Spellcasting 5 and Sustaining 5) which seemed pretty crazy. Thanks a bunch for clearing that up!