My character (retail : Ineveri / Inevero (Archimonde)), server (Inevero)
http://www.wowhead.com/spell=232698/shadowform and http://www.wowhead.com/spell=194249/voidform
You should loose your shadowform when you enter in voidform. When the VF ends, the SF should be applied automicaly (even if you were not in SF when you casted the VF).
Pretty Important.
This lead to an overall +10% damage increase and +10% physical reduction while in burst you should not have
PS : Sorry for the bad english, if something is not understood or have questions, leave a comment or mp me.
NB : All of this have been tested on retail.
NB² : My character is new on the server, i have not unlock all the artefact traits, so could not tested all of them yet.
status changed from new report to report confirmed