Mage/Dark Wizard Sustain build?

Upon contemplating the Majin and Tasim fights, I've come to the conclusion that, aggravatingly, my reliable build of Morph + Cascade does not work. It is not strong enough. It was strong enough for Zhiraok, Zhiraok, and Gikyo, but not for these two. Which is very annoying.

My playstyle with my Lightbender is to run around mainattacking with Ophanim, trying to dodge with Teleport, and, when I remember, shooting off an Ice Snake. I usually spam Heal to heal faster because damage sometimes hits really, really hard. I'd prefer Mana Regen over Mana Steal. I have 16 stx in total but I'll allot three for a new Fruma Murder Build; what would that build be?

 

This probably won’t be three stacks or less, but here’s a Lament build I made.
https://wynnbuilder-beta.github.io/builder/#CT00+00HOl3yQWjH6VGhJOFohcKSfVUwEkcx+0
Heal spell heals 183% of your max health with perfect rolls which should make damage become barely an inconvenience.