PSA: Sculpt spells will not save your party from spells that still do damage on spell save.
 
 Keegen @   Keegen @kbin.social       Posts 19Comments 104Joined 2 yr. ago 
 Keegen @   Keegen @kbin.social     
Posts
 19
Comments
 104
Joined
 2 yr. ago
 
 
 
 
 
 
 
 
 
So does Fireball and yet that one does no friendly fire damage. Either Ice Storm is bugged or it's as the other commenter pointed out, Guardian of Faith detected a hostile action and triggered an attack on all nearby hostiles (your party), which dealt enough damage to it to kill it.