Magic Item: The Witch Whistle

This image has been floating around the net for about a year.  Figure I should do something fun with it.  So here it is for Old-School Essentials.

Witch Whistle (Witch Flute)
Summons an army of rats when blown.

• Summons 10-100 (10d10) normal rats when blown (usable 2x per day)
• Or summons 5-30 (5d6) giant rats when a short tune is played (1 per day)
• Or summons 1-4 (1d4) wererats when a longer song is played (1 per day)

These whistles are created by Pagan Witches and Death Pact Warlocks. Crafted from the bone of a wererat and petrified paw of a rat.  They keep the songs well hidden but allow the magic to be used to summon normal rats.  If the songs are learned the player can use one of any of the powers once per day.
Under any circumstance, the player does not control the rats that are summoned.
They arrive within one round.