Someone posted over at IDB that a
Double Dryer may help a lot, as it reflects air (and his weapons do a lot of air). You can pick one up for under 3K.
The strategy from IDB (requires 125 strength boost):
Turn 1: Freezer, Dryer, Defend (start over if he half-kills you)
Turn 2: Your best bomb plus a good one-use bomb like Water Muffin
Turn 3: Good one-use bomb, Dryer, Burrow
Turn 4: Main attacker, Dryer, Sink
Then he should apparently be dead. I don't know if it works or not. I'm waiting until I've finished training to the 125 boost (half a month or so) before I attempt him again. I did manage to tie him once with the 85 boost, but that was a fluke. He didn't use the ghostkersword or bomb until the last round, and he didn't heal at all. Usually he kills me when he has 35 or so HP left.
I got a 106 boost.. Can i kill it too?
Edit: Almost killed him but still died... Oh man i got a max hp of 401. comeon !!