Caldaros made a big mistake.
He was too arrogant and spoke without thinking.
One sentence exposed his weakness, and without him knowing, doom was already waiting for him.
Lucivar planned this moment from the second he realized Ciri was Caldaros' source of power.
Being the Blessed Oracle, the chosen one, his arrogance knows no bounds, but he knew his limitations.
Countless Loki's avatars had fought against Sunna's avatars, and all of them ended up losing, no matter what their approach was. Some probably had tried to create a wedge between Sunna's avatar and their source, as Lucivar did right now, but none of them succeeded.
This—what Lucivar decided to do—It wasn't a new approach.
So, he has to add more, utilize something only he has.
And that was how he ended up with the idea of showing the cold truth of the world to Ciri.
He was once a good person, and when he learned the truth about the world, he changed.