I am at the part where I fight the Jade Oni. I am level 44 Master Necromancer and my first time with him I went solo. I actually ran out of cards because stupid me didn't have a treasure card that reshuffles disgarded cards back into the deck. I had him down to only 1500 points before I died.
Anyways, any suggestions in what treasure cards would help the most? Thank you.
Treasure cards? For what would you need treasure cards? Jade Oni is life, and you're death, and that means you get +50% damage--and lifestealing, for good measure. If you've done Youkai, then Jade Oni should be a pushover by comparison. If you're running out of cards, perhaps bring your minion and it will do a large chunk of the damage you need.
Perhaps I should concede that I haven't yet tried Jade Oni as a death wizard. But I just did it as an ice wizard (which is also light on damage), at level 44 just like you, and had 17 cards left over, not counting my sideboard (which I didn't touch), nor the iceblade or tower shield for which the card had been used by the buff hadn't been expended. You do have the 40 card deck that you get in Mooshu, don't you?
Sounds like you have the answer - put a couple of reshuffles in your deck and you will be fine. Some people like to carry a large deck, others a smaller one. If you prefer a small one, keep one or two reshuffles in it for fights where you have to do a lot more total damage.