Keep in mind that they also have a bad habit of trying to mob you...so if you are going to nuke them keep in mind that they are lv60-62 mobs have have quite a nasty crit
yetis are 59 devil yetis are 60. yetis are non agro. Since your int you should stick to sonar as long as possible as they have less hp and are mag attack.
Personally I would never choose the yetis as a farming location...either do penon/sonar or wait till you can do some farmin in the caves.
4x pure str blader ...retired
7x pure int s/s ...9 gap farmin
5x wizard ...on hold