Since ash has accused me of not having a cohesive plan, let me expand a bit.
The random Doc shot planI assume this game is balanced, which means that under "normal" circumstances (whatever that means), town has an expected winrate of 0.5.
Scum may attempt to kill the IC tonight for the win. If they do and succeed, they win. If they do and fail, I postulate that they will most likely lose (their winrate drops to W<0.1).
There are two scenarios for today's lynch: We either lynch a 1-shot Doc or we lynch scum.
A. We lynch a 1-shot Doc
Scum has the upper hand now. Say their winrate has increased to 0.55. To make sure they don't shoot the IC tonight, we want for that move to have a negative impact on their winrate. So their winrate should be less than 0.55. Let p be the probability that the IC is protected enough for the shot to not go through. Their winrate is
p*W + (1- p)*1 = 1 - p*(1-W) < 0.55
Thus p should be bigger than 0.45/(1-W), that is, bigger than 0.45/0.9=0.5. Say we want p=0.55 just to be safe. This is achieved, using pacovf's formula, by having each Doc shoot with a probability of 19%.
(1-p) = (1-x)^A + (2/8)*x*(1-x)^(A-1)*A
A is the number of living 1-shot Docs
B. We lynch a Mafia Goon
Good stuff. Scum has a more difficult time now, but not very much so. Say their winrate has dropped to 0.45. They will be more likely to try and shoot the IC now. The same calculations as above yield that p>0.61, so let's take p=0.65. Each Doc should protect with probability of 20%.
C. We lynch the Mafia Roleblocker
Great! This reduces scum's likelihood to successfully kill the IC significantly. Their winrate drops to 0.35. The second term in pacovf's formula, which accounts for the Roleblocker, becomes obsolete. We want p>0.72, again take p=0.75. Each Doc should protect with probability 21%.
D. We lynch the Mafia Strongman
We've probably already won. Scum's winrate is somewhere down at 0.2, and that's a generous guess. The only way for scum to successfully kill the IC is to roleblock the Doc while no other 1-shot Doc targets the IC. We want p>0.89 now, maybe p=0.92. Docs should protect with probability 16%
So here's the plan. Every 1-shot Doc rolls 1W100. Depending on today's flip:
If it is a 1-shot Doc: Target IC if result <20
If it is a Mafia Goon: Target IC if result <21
If it is a Mafia Roleblocker: Target IC if result <22
If it is a Mafia Strongman: Target IC if result <17