That instance should be no problem for a Life wizard, especially now that you have your Lifeblade.
The key to doing this instance is to make a teleport mark before you fight each Boss. Then if you are defeated, you can fill your Health, Mana, and Potion bottle, teleport back to where you were, set the teleport mark again, and have another go at the Boss. As long as you aren't out of the instance for more than a few minutes, it should be just as you left it.
As for the bosses, it's a matter of taking out the Boss's Minion first, then concentrating on the Boss. Sometimes if you take out the Minion and then get defeated, you'll come back to face only the Boss. If a Boss is giving you a lot of trouble, use a Sprite Guardian spell. The pixie will heal you and give you an occasional Lifeblade or Guiding Light (30% boost to heal).