How do I trigger the frosthound imp gangbang?

[Bobonga]

I had it only occur once, after siding with Kas at the Winter City. I had about 20 pregnancies from Imps or the rift cultists, but it never triggered again. And getting fucked by Kas in her forstress doesn't get me pregnant at all.

 

[zagzig]

That's a particular pregnancy that can only occur after the Frostwood encounter and the Winter City encounter.

People might start getting suspicious if champ keeps seeming to get pregnant coinciding with imps attacking the Frost Hound just as the pregnancy comes to term.