Narayanastra (nārāyaṇāstra)

The Narayanastra is Vishnu's weapon, which multiplies into millions of missiles and grows stronger the harder it is resisted. Ashvatthama releases it on the fifteenth day of the war and it burns through the Pandava army until Krishna orders every soldier to throw down his weapons and stand still, since the astra spares anyone who does not fight it. Bhima refuses and is nearly consumed before he is dragged from his chariot, and the weapon can be used only once in a lifetime.