Based on my own stormlight allocation it doesn’t seem outside the realm of possibility that Dylan would have enough for both powers. But even if he didn’t, stormlight can be recharged.
If you were a vig with at least 65 infused spheres, you use your vig shot N1 and then pay the thievery service to get a second vig. There's no world you do anything other than that.
Let's face it: what did Dylan gain by spending 15 spheres? He could've just said he had that ability, and then he would be counterclaimed if he was lying. Instead he spent 15 stormlight for nothing.
Maybe this makes no sense as any alignment.
There are so many assumptions in this post, it's not even funny. Let's run them down:
1) at least 65 infused spheres
2) able to afford vig shot N1
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tangent: What do you mean pay the thievery service? Stealing is a free action, and unless you have a special power that I don't know about, you almost certainly wouldn't get enough from stealing from 1 person to afford a 2nd vig shot. A role power to pay to steal that much from other people sounds like an almost certainly anti-town ability.
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3) No world you do anything else (people do less than ideal actions all the time, especially me as I have established many times over).
4) I spent 15 spheres (wrong)
5) I already said all the reasons I chose to do it in a previous post, so saying I had nothing to gain is just wrong.