This is becoming an issue with low level content, as the smaller the margin the more random and unpredictable is the result. Try good king Moogle Ex on min ilvl no echo - his meteor cast can kill even on full hp with shields, only because it can either crit or direct hit. It’s currently the matter of trying your luck if majority of your party survive that randomness or not. I am sure it was not designed to be uncontrollable.
