Destroyer passive reflect shield--stacks with ISO set shield bonus or not?

I'm trying to focus now on raising Destroyer to run him with Ronan and Throot.

I have him at 5*, and looking at doing some customization. I'm torn between rolling a shield set on him or a HP regen set.

I prefer a shield set if it will stack with the reflect shield that his passive gives him. Remembering that if a hero already has a shield for a passive (eg. Ronan), proc'ing a shield buff only refreshes the shield, not stack it; so if this is the case I will try to get a HP regen set on him.

Anyone use him enough to give some thoughts?

Thank you.