Well im not sure it matters or or not but its only using the actual "/cast spell" for devouring plague
And although vampiric embrace dont cost anything, it does start a timer on other stuff. So its not added in the macro. At the start of the boss pull ill cast shadow word: pain and vampiric embrace to give the tank time for aggro. then ill use the macro. I was boxing 3 spriests in naxx last night and was very impressed. Others in the raid could not believe I was boxing 3 spriest.