What scales attract special units?

[nightrace]

So I'm playing Bogarus when one dark stormy night an ice druid turns up at my door wanting to serve my pretender whose domain is "cold and darkness". I assume he appeared because of my cold and magic scales. Another time a shadow seer appeared because he had forseen my pretender's triumph. Was this due to luck and magic scales? What attracts these independents? If I had death and magic scales would a necromancer turn up looking for employment? Are the scales related to their magic skill, e.g. 2 cold to get ice druids, 3 luck to get shadow seers, etc?