Dark mana was a unique concept that Timothy had never heard of before. Sure he was aware that there were different types of mana, such as psidium, calidum, and flesh mana, each of which had special characteristics and demanded full dominance of one’s mana pool, but he never heard of dark mana! Necromantic powers being dark, apparently wasn't just a figurative speech!
However, formalities aside, Tim cared more about if these new settings would help him complete his plans quicker, cheaply that is! He put himself in danger just to buy the Master's Will ability, and if this thing depleted his mana pool after creating a couple of slaves, then his plan was doomed to fail, doomed from the start!
“Let’s see here…” He muttered, and brought his two new, little pets with him. “I'm going to have to destroy you, boys, but just for a minute! I'll bring you back shortly!”