When specced into Shadow Bolt, Cunning cruelty correctly fires off Shadow Bolts at other enemies. Visually it is beautiful.
When specced into Drain Soul, the Shadow Bolt Volley doesn’t trigger. Cunning Cruelty’s tooltip doesn’t change to suggest any different behavior.
What does occur is Drain Soul’s duration resets and a single Drain Soul damage event occurs to one target.
I hope this isn’t intentional and that DS should trigger a GCD free SB Volley, because it is a great visual effect.