lategame balance . are my concerns true ?

[Graeme Dice]

Boron said:
vampires have fortunately a quite high mr of 15 .

This means that about 9% of the vampires will be converted. This is not insignificant, as they will be among the ranks of the other units, and become the immediate target.

But in a brief estimation i think you need at least about 10 base death skill and use all your gems for fatigue reduction to go to less than 200 fatigue to be able to cast the spell and survive it .

6 death magic plus 7 death gems in the base cost, 1 for skill boosting, and 5 to reduce fatigue. Total cost of 13 death gems to bring fatigue down to about 116.

so all in all perhaps this one single strat beats my vampire horde strat .
fortunately for me though the spell is pretty lategame .
by this time i will be able to wish myself probably .

Your vampire horde is also a rather late game strategy, so you really should include everything else your enemies would be able to throw at you.