Core has UW/FoW
Nightfall has DOA.
Factions has Urgoz/Deep
What about prophecies?
I think Prophecies should have an ultra hard Sorrow's Furnace quest that makes the place harder with a tough boss in the end to drop a chest similar to the new implementation for Kanaxai/Urgoz. ^^ That is all.
Have you ever met the [wiki]Iron Forgeman[/wiki]...?
What is true is that they could make the 'Last Chest' system be available for The Tombs and Sorrow's Furnace, to match Nightfall and Factions elite areas...