Incanter's Absorption-When you absorb damage your spell damage is increased by 15% of the amount absorbed for 10 sec.
Burning Determination-When Interrupted or Silenced you have a 100% chance to become immune to both mechanics for 10 sec.
+ spell steal this-
Bone Armor -Encases the caster in bone armor, absorbing 1.2e+006 damage for 1 min. While the armor holds, spellcasting cannot be interrupted by Physical attacks. (aka absorbs 1.2 million dmg)
Keep 2 horses on you the whole time so you can refresh bone armor over and over... rack up well over 100k spell power and go to work : )