If 300 extra damage (which we are calculating as a 3% probability chance) is not something you are capable of handling at the start of the fight, perhaps you should improve your gameplay. Nobody has stated that the possibility for the perfect storm doesn’t exist or that FSI has no value.
My stance has always been and remains that you overestimate and place too much emphasis on its actual value.
Coincidentally my shaman has 338hp less than your shaman, over 500 less mana and about 275 less ac than your shaman. See the magelo below. Weirdly, despite having this massive gear based handicap I have not struggled with any of these encounters.
Maybe I’m just better at playing shaman? I don’t happen to think I am particularly talented with the class compared to most dedicated shaman mains.
Maybe the likelihood we are assuming to be 3% is actually lower and therefore I have never once experienced it … and that few if any ever statistically would?
Food for thought.
https://wiki.project1999.com/Magelo_Blue:Jolav
https://wiki.project1999.com/Magelo_Blue:Shamwowi