[Caellian]

That's doable, i had something similar very long ago.

Was something like this roughly:

function self.Banzai(self, unit, aggro)
	if aggro == 1 then
		self.Something:SetVertexColor(1,0,0)
	else
		self.Something:SetVertexColor(1,1,1)
	end
end

But did you consider using the build in (Blizzard) threat system, then all you'd have to do is create a default threat function to affect self.threat or create your own threat function and affect anything you want. The latter is what i'm currently using.