Newbie Question about Damage Reduced by %

[Leurocian]

Hail and Well Met,

I have a newbie question about Damage Reduction (like from Shaftstop and Stormshield).

Does damage reduced by % apply to any form of damage (i.e., elemental, physical, magical etc.), or does it only apply to physical damage?

Thanks!
- Leurocian.