I think that part slipped my mind during that time but I’ve updated it correctly in my new and updated version here
For me, I don’t use Dark Theurge a lot because I have other skills which are stronger so I won’t use it every 20s. It is more of a filler skill to me so I feel that if I were to max it, it would be a waste on me and I would be better off having the passive spirits spawn from Invocation. Regarding Invocation vs Ghastly Trail, I have not really tested it out thoroughly to see which actually provide better results but do let me know which one you actually prefer if you manage to try it.