Thx for free unequip event, I can continue my progress in Automaton.

So, here we go.

This is actually old news but you can kill Destina directly stopping her to transform into Ruele.

What you need is a fire elemental damage monster.. 

(RAVI) or (SOL) .. 

But I used them both in my run.

My team is 

M. Hazel with decent speed.

F. Kluri with decent speed. 

Sol with full attack with 40 speed boots

Ravi with full crit damage and low speed.

We need M. Hazel for Greater Attack and F. Kluri for Def Break. Make sure Sol attacks first. If your Ravi moves first due to her S2 you need to restart the stage.