Armoury

The armory door has an arcane lock spell cast on it. Officially, only Ras Nsi, Sekelok, and Fenthaza know the command phrase to bypass the spell (“white feather”). Speaking the command phrase while standing within 5 feet of the door suppresses its magic for 1 minute, during which time the door can be opened normally. The door can also be forced open with a knock spell or a successful DC 25 Strength (Athletics) check. When the characters peer inside, read:

Gleaming scimitars, serpent helms, and suits of scale armor cram the racks of this vault. Large bones and horned skulls litter the floor, and a shield made from the shell of a tortoise hangs on the far wall.
A large skeletal serpent slithers out from behind the racks, raises its head, and says in Common, “They will tell us the passphrase! So Ukurlahmu has spoken.”

A bone naga named Ukurlahmu (pronounced oo-ker-LAH-moo) has orders to protect the armory from thieves, but it struggles to remember faces. It only attacks creatures who fail to speak the correct passphrase. The current passphrase is “black mask.” Characters are given three chances to utter the correct phrase before Ukurlahmu attacks. Before it attacks, the naga uses a bonus action to speak a magic command word that causes two minotaur skeletons to rise from the bones on the floor. The skeletons obey the naga.
Ukurlahmu speaks strangely. When it asks a question or makes a demand, it prefaces every sentence with “It will …” or “They will …” (for example, “It will tell us why it is here and what it wants”). When it makes a statement or answers a question, it always ends its sentences with “… so Ukurlahmu has spoken.”
Treasure
The armory contains ten suits of scale armor, fifty scimitars, twenty longbows, twenty shortbows, and fifty quivers containing twenty arrows each. A detect magic spell reveals an aura of transmutation magic around the shield hanging on the wall. The shield has a minor magical property: words spoken by the shield’s bearer are amplified and sound ten times louder than normal.
The tortoise-shell shield belongs to Sekelok, and only he is allowed to touch it. If a character removes the shield from the wall, Ukurlahmu coldly demands that it be returned it to its hook, attacking if this instruction is ignored.
Navigation
The only way out of this room is the door to the East that leads to the Hall of Serpents.