It was a very dark night, with the moon waning faintly in the sky. Only the cold glints of his flying arrows were the change in color in his sight. Herriot kept on shooting them down, but some could actually block his shots. He had also been running around on horseback, snatching arrows that could be useable for another shot again. When something very bright and noisy entered his senses, Herriot turned and tried to shoot down that explosive.
To be honest, it was headed towards Artie and some other knights that tried to keep her out of trouble. It's just that when he hit it, it didn't explode and changed trajectory instead. He shot down one poacher, who got close, first before trying another shot at the explosive. However, it was already too close to detonate.
A second later, the tick ran out and exploded just underneath him before the horse could run.