I just thought that maybe the game is getting a bit easy when I dispatched the Shriker from an earlier contract without any difficulty, but then this contract quickly shows that it's still pretty hard at times. 

I'm at the recommended level for this contract, but Jenny still easily kills me. She just deals huge amounts of damage when she hits me, and heals far too quickly when she is split up into three wraiths.

Any tips on how I can win this fight?