Impending Doom Poison Occultist - Blast all (non-uber) content. Probably my favorite build ever.

Early Leveling: Aim for the leveling switch tree and complete your normal lab at level 36, taking the additional curse occultist node. At this point you can equip Vixen's, Replica Doedre's, and Windscream. You will need a Praxis ring in your other ring slot and a mana flask to handle the mana costs. Curse Loop: It is crucial that you have 4 max curses for the curse loop to work properly. Be sure that the "throwaway" curse (elemental weakness) is in the top-left slot of your Vixen's entrapment. Misc Info: You must get -mana cost on both of your non-unique pieces of jewelry or it will be extremely difficult to sustain casting. Avoid as many mana rolls on gear as possible so that your ES pool is as large as possible relative to your mana pool. Try to fit in as much non-damaging ailment effect as possible (helmet, ring) to get near the 40% chill cap for Shaper of Winter. Some form of curse mitigation (Watcher's Eye, Witchbane, Balance of Terror, Flask, Pantheon, etc.) is necessary for annoying rares that reflect curses. Be sure to anoint Skittering Runes for AOE and mana cost. Make sure that you DO NOT exceed 3.78 casts per second (with no cooldown reduction), or you will run over the cooldown of Vixen's Entrapment and lose DPS.