[Setup] VJK

[callforjudgement]

Is JK + Vig versus 2 scum going into night a scum win (due to scum = town), or play on (because town can block one scum and shoot the other)? That may well have an impact on the balance, and is something that needs to be decided in advance.

Anyway, I agree with the other commenters that this is townsided. (A simple experiment that should convince you of this: if town massclaims day 1 and no-actions every night, which is clearly a terrible town strategy, the game effectively becomes a 5:2 nearly-nightless with a scum kill day 3. That's almost balanced in its own right (mildly scumsided, but only mildly). Now give town the power to kill, block kills, keep their role secret until they're about to be lynched, etc., and it's clear that this is mindbogglingly townsided.)

[callforjudgement]

Breaking strategy for town: vig never shoots until a kill is stopped (except in the unlikely case where the vig and JK are the only town players left alive); JK focuses primarily on players who are considered good lynches; both town power roles claim at L-1 or lylo.

If the JK stops a kill, JK claims, lynch the JK target (they were looking like a good lynch anyway), and then the vig shoots in the following night. This should give town an overwhelming advantage.
If only one scum is left, anyone the JK targets is confirmed as town if the kill goes through that night, and if the kill doesn't go through, it means that the vig (if still alive) effectively buys town an extra lynch.
If 3:2 lylo is reached with both power roles alive, lynch in the VT claims (unless two players claim the same power role; if two players claim vig, no-lynch and have those players shoot each other, if two players claim JK, lynch within the JK claims).

All this doesn't guarantee town a win, but they clearly have a huge advantage.