There's no pleasurable way to do this in data editor. Feedback is in not helpful here, cause damage effect just has a field that does damage equal to % of target's vital, then runs modify unit to clear unit off energy. Sadly, you can't just "run effect x times based on caster's vital".
One painful way to do this, is using Persistent effect to drain 1 energy and apply 1 trash behavior, and at 0 energy run another persistent that restores 1 and creates unit for every 2 stacks of behavior on the unit. (somehow attached, thos it still creates +- 1)
IMO trigger editor is much easier to do this kind of stuff, if you dont have 200 units using that ability it shouldn't be too intensive.