As long as you can immediately heal, keep life minimal. This minimizes how much you need to invest in healing. Gala prevents being ista-killed on first hit taken. Not sure Healer is the best class. Was insta-killing levels after mid-game. Astrostoicism was level 4 until last couple dungeons. I think that allowed me to two-shot final boss. Otherwise Master Repulsion buffs astral/psychic damage plenty for the grunts.