Before having completed quests in the area, Argent Crusaders are roaming the Valley of Echoes, fighting with Nerubians. Some number are bound in webs. Forgotten Depths Ambushers are at various places.
Guns appear on the towers. The Valley of Echoes is filled with scourge of various sorts, and an occasional Frostbrood Destroyer joins the fight.
Argent Crusaders once again wander the Valley of Echoes, but cleaning up the few remaining scourge.
Various NPCs appear at (or move to) a camp at the north end of the Valley of Echoes, just shy of The Breach.