Though each single instrument of the jann was a powerful magic item, the true power of these instruments was unleashed when combined and played together. A group of bards or rawunin playing these instruments under the direction of a skilled sha'ir was capable of summoning an army of genies. This army encompassed four genie units—one for each of the major genie races—each measuring 100 strong. Each of these units was under the command of a powerful noble genie. In order to summon the genie army, the musicians needed to play their instruments uninterrupted for a full hour. If the music was interrupted in any way, then the genies who had already arrived would not be under control.
A successful summons granted the sha'ir complete command of the genie army for 25 hours. The genies returned to their native planes when this time expired. All genies serving within this army would not be able to harm the sha'ir for the next 101 years.
Given the power the takht had over genie-kind, most genies and genie servitors were on the constant look-out for anyone attempting to assemble a complete collection of these magical instruments. These collectors were known to disappear or meet otherwise unfortunate ends.