(Dungeon master) One of the knight spoke up " those tracks lead to the water." The leader looked around" Do you have a thunder ball Bellin?" One of the knight nodes and reaches in to a bag and grabs a large black ball with a fuse in it. At the same another knight pulled out some flint . The leader then took the Thunder Ball and said "lite it" the knight with the flint then scraped the flint to gather and lite the fuse the lead knight then Yelled " Thunder!" and throw it in to the river where the tracks ended and it began to sink in to the river the fuse still lite and burning as it sunk to the button  passing by the elf (detonation next Dungeon master Post)