Yes, this method really helped. The only thing is, I made changes for a specific map, not the entire client.
But then another question arises: I reduced the values for the ManaSteal ability to 0.1 per level and SyphonMana to 0.05 per level. After that, I went into the game to test it, and in battle, the demons drain 0 mana.
So, the question is, is this related to the game not being able to read non-integer numbers? And is there anything I can do to make it work?
And an off-topic question: where can I change the stats of the summoned phoenix (HP, min-max damage)?