Blood?

[General Tacticus]

Let see, researching Blood 5 should cost 300 rp, a good research pretender can easily do that by turn 20 if he does very little else.

Now, you need to have 55 blood slave by turn 20. No problem. But what you really need is to have an income of 55 blood slaves, say at the very least every two turns, with enough over to still spread your dominion. That means, I would say, about 10 mictlan priests (let's use Mictlan) on permanent blood hunt, by turn 20. Plus a way to bring the slaves back, either labs or scouts on carrier duty. (I assume you are not blood hunting in your capital, which is your main source of gold)

I would put that setup at 1000 gold minimum, plus half the commander recruiting capability of your capital. As a rough guess, you have been spending 20% of your gold income on the setup. You would be hard pressed to do some serious site searching at the same time, so no gold from alchemy. And you still have to expand, without your pretender...

Yes, it looks like it can be done, on paper. Still, that 20% of your income will be missed elsewhere : for building additional fortress, province defense, even plain old armies... You also need more priest on sacrifice duties. Not to mention the fact that your good research pretender has cost you a lot of points, so your scales are not that good.

I haven't tried ice devils, so I cannot say how good they are, but would you say 1 Ice devil every two turns is worth investing 20% of your income for the crucial 20 first turns ?