Rift Quest:The Taking of Overwatch Keep  

When any of the items needed for this quest are clicked on three mobs will spawn. Two standard level 20 Aelfwar and a level 20 elite Aelfwar Curator. It is highly advisable that you bring friends. However if you do die you can run back and spawn away from the mobs. As long as they have not despawned you can loot the object without fear of retaliation.

The items can be found in these locations:

Greenscale Blade of Growth - Top of the tower on the table at 6400, 3170.
Greenscale Faestone Bell – Top of the Tower on the pole at 6386, 3066.
Greenscale Tome of Life – Top of the Tower on the table at 6502, 3190.