Simyaz was the leader of the githyanki party sent out after the blade of the sacred Silver Sword stolen by Irenicus. The blade was subsequently given to Saemon Havarian, who knew it could only bring trouble and was anxious to be rid of it. Simyaz's group went after him in a levitating ship, but it was somehow capsized, possibly by the same sahuagin who may have attacked Havarian's ship. Simyaz and a few other githyanki ended up taken prisoners by the illithids living near Ust Natha, forced to fight for their amusement.

The player character will encounter Simyaz and his group for the first time at sea if they choose to take Havarian's offer to come aboard his ship and sail out after Irenicus. In that case, the githyanki will attack the ship, only to be interrupted by sahuagin sinking it. The other time Simyaz can be encountered is if the party decides to enter the illithid caverns when working for the drow in Ust Natha. There, they will immediately find themselves captured and put into the cell next to the githyanki. Simyaz will then offer to cooperate in escaping the illithids, the player's party fighting them and the githyanki using their mental powers. The githyanki will teleport out and leave the party to fight the illithids. If the party has or had the Silver Sword, Simyaz's group will face them for the final time in the main cavern outside the illithid city. There, the player is finally given an option to simply relinquish the blade, although the githyanki may still decide the player character is unsavoury, and attack.