The pieces that will yield a Sleeper's tomb key are as follows
A talisman from any of these 5 dragons:Zlandicar(Dragon Necropolis), Klandicar(Western Wastes), Yelinak(Shyshrine), Sontalak(Western Wastes), Lendiara the Keeper(West Wing Temple of Veeshan)
a shard of Hsagra's Talisman from any of these mobs:
King Tormax (Kael Drakkal), Derakor the Vindicator (Kael Drakkal), Statue of Rallos Zek (Kael Drakkal), Velketor the Sorcerer (Velketor's Labrinyth)
The Idol of Rallos Zek DOES NOT have a chance to drop the shard, it drops nothing, and I have never witneseed a drop from The Avatar of War, I don't believe he drops it.
You can have a rogue with 210 skill and 2% mod for at least 214 total skill pick Jaled'dar's door, or you can kill vaniki and zland, and take both of their hearts to Neb for a key to his lair, alternatively, you can kill Neb ann take his head to Zlandicar, keep in mind both of those turn ins take faction.
I don't believe any faction is needed for the talisman/shard turn in for the Sleeper's Key.