Quote Originally Posted by Arial Black View Post
Spirit Shield reduces the damage that the rogue takes. The damage that the rogue takes is half the source damage (if Uncanny Dodge is used). Spirit Shield has no effect to reduce the incoming damage, only to reduce the damage taken, which has already been halved in this case.

So, Uncanny Dodge first, Spirit Shield second. It could not work the other way round, because if the rogue takes full damage he already didn't use Uncanny Dodge to half it.
To put it another way.
UD triggers when hit
SS triggers when damaged.