I like that you are on a possession/GoR high. But I don't totally agree with all your conclusions, some sound a bit, inefficient. I would rather get a Sleeper to fire the crossbow. Prec 15. Good thug chassis, great leadership, only 8 gems, and your mage lives.
Did you find any other units that have hidden magical paths? (These I have found so far:
http://dom3.servegame.com/wiki/Gift_of_Reason )
And you can confirm that the mercenary doesn't disappear when you stop hiring them? (Aka, you tested this?).
And what was the disease demon bug?
And while I keep asking questions, could I have a water gem?