Battlemage.
The Battlemage is one of the best PVM (Player vs. Monster) mage templates around. His high LIFE and WAR skills allow you to drop a vuln and kill with a war very easily without having to debuff your opponent. The only downfall to this template is the help you will need getting to level 50 - this is when your character gets CREATURE magic!
You should always start a full mage with 100 FOCUS and 100 SELF. The other attributes can be customized to your liking. If you can get a lot of twinking and care in the early (1-30) levels, you could opt for taking this character very extreme by starting with 100 STRENGTH.
Post 50 you get to choose from either Healing @ 80, Lockpick @ 80, Leadership @ 70 or Arcane @ 70.