The easiest time I ever had getting mage kills as a pre-applicant and applicant was with a human thug thief.
You can put out a lot of damage and can surprise people, which leads to dead mages.
I think I had nine mage kills pre-induction with my not-very-memorable thief.
Also, I went defender and was a great explorer, if that interests you.

The second easiest is assassin. Being able to see invisible is huge, even if your tactics are limited pretty much to trip/throw.

Contrary to popular opinion, svirf is not an easy choice for ease, because every single mage will sit in their guild and assume that you're going Battle.

As for your role, I've gone with everything from "I literally cannot stand the smell of magic" to "mages tried to turn me into a giant ox" which is a variation
of "mages burned my village down" but allowed me to emote having a tail.