Small, normal stones which have been modified through the use of sorcery to discharge a small explosion, or flash, at an enemy during battle.
A flashstone is discharged at one's opponent, apparently requiring only the will of the user to activate.
A flashstone is normally fatal at close range, say 10–12 feet. Beyond this range, the effect is limited to a bright light that may confuse or injure (but not kill) its intended victim.
A typical flashstone will carry a single "charge", meaning once it is discharged, it becomes an ordinary stone again, and is simply discarded.
A person skilled in sorcery may be able to add additional charges to a flashstone (as many as four per stone), but it becomes increasingly time consuming to add each additional charge to a single stone.