The Roach Mage is considered the most defensive mage template that you can possibly build. With the use of parrying and healing you become a force that is extremely hard to take down. With no weapon skills you lack offensive damage but will make up it up with your defensive capabilities. This is likely a very strong template for Paladins considering the paladin shield will allow you to cast with it equipped.
Roach Mage Template
100 Resisting Spells