Bright Mages Forbidden

My younger sister is marrying an unscrupulous dark mage! Well, he himself seems to be a decent guy, but his brothers are definitely unscrupulous! A necromancer-misanthrope, an incubus-lover, and of course, the main evil - the dark lord. And all three are so happy about the wedding that it inevitably raises the question: are the future relatives planning some kind of trick? So I will have to, as the best in protection against dark charms, sort this out. I won't let anyone hurt my sister and I will defend the family honor!