End of the day are we raiding? Pvping? dungeons? Just having fun?
RE Spectre: seams like a pvp talent but DoTs do 10% more damaged while stealth. Fits the theme of dot and disappear (Having a pet out for pve to keep it from reseting)
RE Consumed by shadow: leaving stealth puts you in shadow form, your spells deal bonus damage coming out of stealth. Fits the theme to DoT, stealth, unstealth into mage
RE Shroud of concealment: Stay in stealth for 1 bonus second if you break stealth with a mage spell. Wonder if we can work a rotation around DoTing up, stealthing, and then doing a long mage cast in stealth to not have much downtime? Don't think there is a great option here.
Legendary RE: Curse of Arugal: Combines shadow priest & Feral cat playstyles. I havn't used this one yet but that can get you into combo point using abilities & spells. It's likely a 'stance' so it wont work with shadowform
We have a few REs and talents that work around 'shadow dance'. In ascension you can type any word into the character advancement search box or RE search box to find even partial text within the description.
Legendary RE: Master of shadows: This is more of a shadow damage rogue that works with instant cast shadowbolts. It could be a fun base tho.
I'm just searching the words "Stealth" "Shadow dance" "ambush" "Garrote" in the RE interface to see what comes out. You might be able to make a DoT based Shadow dancing vanish boy