You need either HasteForge event, and some kind of +haste item, or, you need to kill them really darn fast.
Do not be affraid to trade health. And prepare some free space. Their curse rotation will kill you either by direct curse damage, or ramping regen and rage.
Best fast-kill canditates are archery, and burst mage.
If you are not running a status build [haste, rage, regen] you can make really good use of Cleansing potions.
