Curate, connect, and discover
One thing that makes the mind control in the Divine Tree arc sooooo creepy to me is how much the brainwashed characters still act like themselves. A lot of the time in fiction when characters are mind-controlled they become zombie-like or robotic, with their original personalities suppressed. Or sometimes they become actively sinister, an "evil version" of themselves.
Obviously Divine Tree doesn't do that. Dimple's telling the truth when he says he hasn't changed anyone's personality, he's just given them something new to care about. "A blessing for those who have nothing and long for a place to belong." And that's horrifying. Both because it feels like in some ways a deeper violation than simply making someone pretend to be a person they're not, and because it means that the effect it creates is basically the same as people who have been taken in by cult rhetoric in the real world. The Divine Tree doesn't use magic to create effects that can only be achieved by magic; it uses it to speedrun the radicalization process.
The Divine Tree Arc isn't the horror of having someone you know replaced by an alien consciousness. It's the horror of knowing that the person standing against you is really your friend, your classmate, your brother, your mentor--they just care about something new now. And it's the horror of knowing that when push comes to shove, they're always going to care about that new thing more than they care about you.