Generally speaking shroud should be the first mythic for almost every build. However if you’re committed to sticking with DT this is one of the few builds that uses a unique chest.
Heir would be the bigger dps boost if you wanna stick with DT.
Craft shroud though if you want to play other builds.
Interesting, since I'm pretty set, Shroud seems like a good option if I decide to just keep my helm. I think Heir would be ok, but I'm unsure if the trade-off on losing almost 1k health is worth it or not.