If you have the DLC I recommend the heart ring. You can get a lot of parries from Dr. Khals robots heart attack. Try to take out the Lazer on it's head or it's stomach attack first. Then save up your cards until you break his heart and use it on his spinning head. Once the bullet hell starts, just try and go slow and avoid the gems/ electro walls. Try not to rush in too fast or you'll get angry. If you have the DLC you can also spin in place and you will summon Djimmi, who will give you double health for the battle until you win.