What act of a mythical hunter-warrior of Irish mythology won him the leadership of the Fianna?
Aillen:  This only ended with the arrival of Fionn mac Cumhaill, who inhaled the poison from his spear to keep himself awake and slew Aillen. Aillen:  The act won him the leadership of the Fianna. Fionn mac Cumhaill: Fionn mac Cumhaill ( ; ] ; Old Irish: " and Middle Irish Find or Finn, mac Cumail" or "Umaill" ), sometimes transcribed in English as MacCool or MacCoul, was a mythical hunter-warrior of Irish mythology, occurring also in the mythologies of Scotland and the Isle of Man.
inhaled the poison from his spear to keep himself awake and slew Aillen