Why does Secrets and Shadows Challenge Tier 3 exist?

I have R7 Daka @148K health with Crit Avoid arrow. If you balance it carefully, using a Talzin lead you can have Zombie and Talia die off at least 12 times or more through the first 3 phases. Each revival gives Daka 10% health increase (Stacking). But it is all for nought as Sidious AOE usually kills her first go. She has survived this initial once for me but another AOE comes around too soon and always takes her out.