Stygian Ice Whistle

The Stygian Ice Whistle is a whistle given to Percy by Daedalus. Percy later used it to call Mrs. O'Leary.

Physical Description
The Stygian Ice Whistle is made of ice from the River Styx, as such, it feels unnaturally cold while on the hand.

The Battle of the Labyrinth
Quintus (Daedalus) gave Percy a Stygian Ice Whistle before Percy left on a quest into the labyrinth, explaining to him that he can use it to call Mrs. O'Leary when he is in trouble, and can only be used once. Suspecting Quintus as a traitor Percy delayed using the whistle as long as he could, he nearly used it when he was cornered in Mount Saint Helens by the telekhines. Later, after defeating Antaeus, Percy was forced to use it as Luke's army surrounded him, the whistle shattered in his hand and the shards melted, a moment later, Mrs.O'Leary appeared. Mrs. O'leary wiped out lukes army as chirons legs broke.

Abilities

 * The whistle can call Mrs. O'Leary. It can only be used once. After that, the whistle melts.
 * Just like Percy's sword, Anaklusmos, the whistle returns to the owner if lost (as demonstrated when Percy was sent to Ogygia, and the whistle was still in his pocket)
 * The whistle does not melt unless it is used.When it is used it is shattered.
 * When used, there is no sound (at least not of a pitch that humans can hear)