A large and high energy portal opened up high on the hill in the crossroads. Several attempts were made to disrupt it with Modenkinens disjunction and other ideas but all attempts failed to break the incredible level of energy sustaining the portal. After balors came through, the portal master ,Zsalat himself, appeared within the portal but seem to be somewhere untouchable.
He offered and pleaded with the adventurers there to join his cause against Myth Drannor.
After he was done making his point he forced drow through the portal that he deemed 'rebellious and uncooperative' to be disposed of by the adventures , which the summarily did. Zsalat thanked them for helping him 'clean house'.
To anyone who is able to sense the nature of the portal, they might be aware that this was more of a rift than a typical portal. To anyone who could perceive more they might realize the origin of this portal was not the abyss nor was it the negative plane. the actual point of origin would be unknown however