Open GameMechanics/RPGStats/DefaultStats.xdb and find this:

Actually you need this only:

And here are the lines with numbers:

First line 1 is for the base dark energy (DE). Originally its 200, this is your starting amount, change the 200 and you’ll start with more or less.

Line 2 is for the DE bonus per level of one of your heroes currently its just 1 per level

Line 3 - the DE bonus per 1 Pillar of Bones (150)

Line 4 - DE bonus for Grail Building (150)

Line 5 - every creature in H5 has its own power rating (PR). The DE cost per 1 creature is Creature Power/25. If you rais the number of this line, you’ll need less DE per creature. For example the zombies have PR of 105, the DE cost is 105/25 = 4,2 per 1 zombie.

Line 6 - you don’t realy need it.

After line 7 you have the transformations according to the first one the peasant will turn to skeleton (through your Necromancy skill). If you change it to:

 <Item>
     <Dead>CREATURE_PEASANT</Dead>
     <Rise>CREATURE_VAMPIRE_LORD</Rise>
 </Item>

You’ll get Vampire lord for peasants… and that’s all…