Srutayudha's mother had wished for a boon from Varuna for his son so that he could not be slayed by anyone in battle. Since he cannot grant immortality, Varuna instead presents a magical mace to Srutayudha by using which he would stay undefeated in battle.
Varuna had also warned about the adverse effects of this weapon if it was used against an unarmed opponent. According to the warning, the Mace would strike back Srutyudha himself if he used it against any unarmed person.[1]
On the 14th day of battle, the Kamboja army division is being assailed by Arjuna as the latter is attempting to reach the end of Drona'sPadmavyuha. Rescuing Kritavarma, Srutayudha, from atop his elephant, challenges Arjuna, striking Arjuna with multiple arrows. However, Arjuna counters, snapping Srutayudha's bow. Filled with wrath, Srutayudha hurls his mace at Arjuna, but Arjuna hide behind Arjuna's unarmed charioteer Krishna, who received that mace. As per the conditions described by Varuna, the mace boomerangs back on Srutyudha killing him.[2][3]
