yup it's kinda lotery but when he will one hit u with range u are sure that it's good distance and he won't hit u for 2k.
However it is bug that what show guy on 3 post in his movie.Isoolion never (normaly) range atack guy 0.5 meter near him.With that bug it's just like uruk thorn with big hp and good drop.
Btv how u bugged him mabe I will came on 5 min to isoolion floor with friends and kill him quickly before someone will see :P :P
anyway I must say they killed him not so faster than in normal way (if it was faster)
PS: that think with atross wasn't best example coz he hit sometimes with flame even if u are actualy in him :P