Near Stonecrest fountain, you will find a NPC called Tristan. Talk to him

and say "Yes", "Yes", "Recently", "Digging" and 
you will hear a story about two men digging the ground with shovels. They 
found a corpse of a Seraph and head east with their caravan.
			
			Go east 
and follow the path that is heading to spiders. Just before you see spiders 
you will see a small camp with Obsidian Conclave Knights. Attack and kill 
about 10 of them until their commander spawns. Kill Commander Mordred and 
you will find a small iron key. With the key, open the chest that is located 
near the camp. You will find the Celestial Plate.
		
			
Quest Reward Synopsis:Ancient Celestial Plate (Reqs: 100 
End, 30 Str, 30 Agi, 30 Int, 30 Wis, Seraph)