I'd like to see King Radovid not actually insane and instead a cunning manipulative, but thoroughly evil bastard. I'd also like him to be completely evil and ALSO TREAT GERALT WELL. I'd like to put the players in an uncomfortable position, for example, of having Radovid's patronage while he's completely amoral.
For example, I'd like for you to be able to speak with King Radovid on his boat anytime you want and have him as someone you can ask questions about and talk to him about his invasion plans.
1. Why are you supporting the Witch Burnings in Novigrad?
I don't support the persecution of nonhumans or witch-burnings, actually, Geralt. I pushed the Eternal Fire into doing what they did because I had to. The Conclave is something I intend to resurrect to its previous glory and that's not possible with groups like the Lodge. Every wizard, mage, and sorcerer in the North is coming to me for refuge because of the Eternal Fire's actions. I've also eliminated the one place they could all flee to stay out of the war. Now, they have to side with me against Nilfgaard or expose themselves as traitors. When Novigrad is mine, the Eternal Fire will be...chastined.
2. Do you really intend to restore the old borders?
Oh yes, that's how I convinced Kaedwin and Temeria's nobility to support me. Of course, that doesn't mean we can just keep things the way they were. Nilfgaard has shown itself to be too powerful to continue the old way. Instead, we're going to restore the Old Borders under a permanent military alliance with a single head of state. All of the lands will have their kings but they will answer to me as High King and we will maintain an existing standing army to enforce order and guard against the Black One's aggression."
3. What do you intend to do to Triss and Yennefer?
They are both members of the Lodge of Sorceresses but I have a simple enough offer to you, Geralt. Bring me the head of Phillipa Eilhart and I will give pardons to both your lovers. The Lodge must be exterminated and its ashes scattered for the death of my father but you will find me most generous to my friends.
There would be a questline where you could then assist Radovid in hunting down Phillipa Eilhart and killing her, or you can choose to side with Phillipa and kill Radovid. If you do the former then Radovid's forces will back you up against the Wild Hunt and if you do the latter then Phillipa will back you up with her Nilfgaardian friends.