I really wish they had come up with a better name than Scion of the Three, because I find it too setting-specific. If I wanted to use it in, say, Exandria, I suppose I could alter the three gods. Bane exists in both realms, but I’d have to change Bhaal to Gruumsh and Myrkul to ….. Vesh, I guess.
Still, they could have gone with something like Scion of Death or Scion of Malevolence rather than tying it to three specific gods. Then it would have been more setting-agnostic (but then they’d have to alter the Dread Allegiance feature, unless it has already been altered sine the last UA).