Lancelot
Adventurer
I wonder what the point of having the Erinyes, if the Succubus fills the equivalent role. Having the Dretch will be nice, although I'm surprised no quasit.
As per 3e, the erinyes hasn't had an equivalent role to the succubus for many years (since 2e Planescape). 3e repositioned her as more of an angelic avenger: raining down fiery death with her longbow, or cutting people apart in melee. I'd expect the same in MM2, which is Good Stuff. The 1e/2e image of the erinyes was pretty far from their mythological origins as divine furies of vengeance.