"Ah, we are joined by another." Gav said as Kovinth slipped in. He stood up from the table, took his cane and made his way to the door. "But I've overstayed myself. I must make haste back to Arussia. The three of you have a long job ahead of you." He unlocked the door. "I expect I will be hearing from you sooner than I hoped." He opened the door and stepped out, closing it behind him. 

If anyone were to open the door after him, they'd find an empty hallway, as if Gav simply vanished and were never there. In fact, the only hint of his presence was the castle layout left on the table. Everything is in the Planeswalkers' hands now. They know their mission and where they need to go to complete it. It's now simply a matter of getting it done.