Y'know, thinking about it, Jahy's going at this the wrong way.
In order for Dou to conquer the world, she can't make Dou do 'evil' things.
She just need Dou to do 'good' deeds that result in the humans submitting.
Like in this chapter, Dou initially wanted to 'heal' those things, but even after seeing that it had negative effects on them, Jahy still could convince Dou to heal others too.