Maelle “One-Shot” Build. What am I missing?

Alright best way I know how to do this is just to list Pictos and discuss the facts. Fact: I’ve never gone above 4 million damage with Maelle from a single hit. This is after using the Burning Canvas attack. Here are my associated Pictos:

Feint, Draining Cleanse, Frenzy, Double Third, Double Burn, AP Discount, Auto Powerful, Alternating Critical, Cheater, Confident Fighter, Critical Burn, Glass Cannon, Gradient Overcharge, Immaculate, Teamwork, Warming Up.

I’ve also switched out Draining Cleanse for Inverted Affinity and Tainted before. And throw in Roulette every now and then. And I’ve also applied Sciel’s 50% buff. I’m using the Medalum weapon. What key component am I missing here?