Adjusting the formula for the mana-draining abilities of Imps, Devils, and Lesser Devils.

Hello everyone. I have a question: how and where can I change the formulas for the abilities of Imps, Devils, and Lesser Devils? I found on the wiki that 1 Imp and 1 Devil steal 0.25 mana per creature. A Lesser Devil steals 0.125 mana per creature. I need to change these values. I searched through the xdb files for the creatures themselves, but I couldn't find these settings, just as I couldn't find the settings in the xdb files for the abilities themselves. Can you tell me where I need to look?