Not too surprisingly, my answer would probably have to be Eternal Aura and one of the Avatar forms. Aura was clearly designed with them in mind, so it's no surprise that they work so well together.

Trying to think what else I particularly like... Mystic Regen and Vow of Silence is nice, provides decent regen (particularly if you cast another enchant first, something like Faithful Intervention is perfect), and helps mitigate the main disadvantage of using Vow on a physical attacker (that they can't be healed). A lot of the assassin critical strikes skills synergize together particularly well, too. Being able to constantly sustain IAS, extra armour, 75% blocking, healing on most hits, and the impressive critical damage of a scythe on multiple opponents.
