I have been saying for months that upgrading offensive Runes, Gear and Talents throws off Banish damage. I go through the same thing every week, and have been for months... I've given up trying to figure it out for several different reasons, but the biggest is that it makes so sense what so ever and is so frustrating that if I think about it for over 5 mins, I feel like breaking my monitor. I deal with it, and the damage level's out after a few weeks.