A syrinx is a weapon used to fill vials with blood. It requires 25 Attack to be worn. Syringes can be bought at the Canifis general store for 1000 gold coins. To fill a vial with blood, you need to be wielding a syrinx and hit a 50 on another player. If you hit 100 you will fill 2 vials, 150 will fill 3 vials, etc.