just in case you ar estill working on randolf i reccomend hitting him hard and quick, dont shield up or put any blades on youreself just hit him as many times as you can as quick as you can and also mabye go up a few levels before facing him again
What you do is spend your time putting traps on him and yourself. Negative to yourself, maybe a couple plus 30's, but add traps to him, then use a really strong storm card. I used one that killed him in one hit.
Buy a bunch of storm treasure cards. I bought two traps, two blades, and some of the bigger spells. Have those as the only treasure cards in your deck, and then draw them all. It worked for me. :) It's the easiest way - just make sure to have some healing cards on hand just in case!