So how about instead of completely overhauling Decoy you just give players a choice if how to use it. Make it so when you use decoy you can are invisible as usual but you can also warp. However if you attack or use abilities you become visible and the decoy still works as it would until the duration ends. That way, brawler Wraiths get their fun, stealthy Wraiths get theirs without impacting how you marketed the game and the whole assassin aspect isn’t completely flushed down the toilet.
If this new take on decoy is made just rename it “Doppelgänger” since that’s what it is.