Morale 15 is a useless saint bonus when you hit 100 morale

[Legolas Bow of Athena]

WAIT! HOLD THE PHONE!
I know when a +15 morale sainiting is useful

when you get 7 of them on one hero
then you free up your morale rune slot for something else

well played sir, however i can't give you credit as an endurance rune is a must so that slot will not be able to be free. I do appreciate the thinking though lol.