Around midnight, Luke and the others had dealt with most of the Salamanders, so it was time to approach the enemy base. However, he told them to buy some supplies before the attack. Aside from some tier-three potions that restored eighty mana points, Luke also bought a skill book. It was called Stone Cannon and could fire a projectile the size of a fist. Luke tried to cast the spell against his hand to see if he could reuse it, but the projectile fell apart after a few seconds. It was different from Earth Wall.
In any case, Stone Cannon cost five MP, the same amount as Spark Ball. However, it was a lot more silent, so Luke could use it to silently snipe the enemies when he is running low on needles and nails.
