How to vassalize a faction in tw3 ?

[Evono]

title

[Maelos]

Either attack and capture their last settlement or diplomatically vassalize them... Not sure if that's a normal diplomatic option, but Slaneesh's (N'kari) campaign mechanic is literally made for that. Just wait till they are fully seduced and you can vassalize them.

[Evono]

Originally posted by Maelos:

Either attack and capture their last settlement or diplomatically vassalize them....

hmm how with diplomatic ? i have allys with +200 that still say -40 on vasall setting or even -69

[Mr.Person]

Because Vassalizing somebody is usually a hostile act. The highest thing you can do between friends is a military alliance