Counter attack and Sturdiness
I agree 100%
This is why ZS nerfed Titanium Shield and 1* 1.1 heroes
You also want to consider the Defense stat, and HP, of the other 2x to 4x heroes getting counter attack buff
Dead heroes
Once a fragile hero dies on your team, they are no longer targeted by enemy special skills, and normal damage / tile damage / matching damage
This concentrates the attacks on fewer heroes
Counter attack nearby versus all
Counter attack all is helpful once one of the heroes next to Boril dies, since that immediately cuts
b.Boril counter attack from 3x 1.25 to 2x 1.25 ( effectively 3.75 for whole team to 2.5 for whole team )
c.Boril is cut from 5x 0.6 to 4x 0.6 ( effectively 3.0 for whole team to 2.4 for whole team )
FIN