Yeah Avernus is a bit of a dead end when it comes to a DLC, not to derail the thread too much but most believable theory for me at the moment is that the DLC (if there is one) will be related to Cyric who was alluded to in the epilogue in a note on Withers desk, another god who has history with The Dead Three, Mystra and Shar, Larian seems to like getting mortals and gods to interact so it would make sense from that point of view.
