Already met it in T50 twice before you posted this (both you, Jmdt, and Luis-something).
It was quite fierce, but could beat it with ease with your own Healbow T50 version.
The heals certainly make it hard to beat, and those come out consistently. I don't think the Chaos Powers are the best choice without an Entropy mark however.
My suggestion would be:
- 3 Chaos Power
+ 2 Explosion (for both AI3 and T50 this seems vital to me, those shields....)
+ ehm.... wings/fog/charger/wyrm/precog?