Truestone is a form of mineral which was a part of the primeval mountain called the Spike. It is a piece of Acos, the primal God of Law, who died when the Spike exploded in the War of the Gods. It has many remarkable properties.
One of the most important is that it can be used to store magic points, spells, and other magics, such as the Lhankor Mhy custom of storing secrets and knowledge in them. They may be used for this over and over, but once part of a Truestone is ‘set,’ that part cannot be used for any other purpose. A Truestone has a capacity of 3D10 pts.
For example, an adventurer may take a blank Truestone of unknown capacity (there are very few unset Truestones known, but the Spike was a very big mountain) and put 10 pts. of spirit magic into the stone. That stone can now store any 10 pts. of spirit magic. Rune spells are double ‘cost’ so when they then put in 6 pts. of Rune magic the Rune spells occupy 12 pts. of the Truestone’s space. Knowing they may need extra magic power for her next mission, the adventurer attempts to store 10 magic points, but discovers they have reached the stone’s limitwhen only 7 magic points are stored. The stone has an impressive 29-point capacity. However, as far as the adventurer is concerned the stone can store 10 points of spirit magic, 6 points of Rune magic, and 7 magic points.
One quirk of Truestone is that any spell put into it is still active. For example, if an adventurer puts Bladesharp 3 into the stone, they must use the Bladesharp 3 spell in the stone before they can use the spell again. Placing the spell into the stone creates a sort of blank space in the user’s spell inventory. If the adventurer loans the stone to someone else, and then has a need for Bladesharp, they must learn the spell again, and have space in their spirit magic capacity (up to CHA) to fit it in, because the stone version still occupies that space. The same applies to Rune magic. The user is putting active Rune spells in the stone, and those Rune points are no longer available to the adventurer until the Rune spell is used. Fortunately, this effect does not apply to stored magic points.
Anyone can use these spells and magic points, not just the one who stored them. They are often gifted by kings and queens to supplement the power of a single agent on a dangerous mission. Sorcery spells put into the stone function exactly as they were placed, with no variance. The sorcerer cannot use that sorcery spell until it has been used from the stone.
Truestones can also be used as sling ammunition. They do normal damage but ignore Protection and Shield spells and act as attack spells with a POW equal to the number of Rune points in the stone for the purpose of knocking down Countermagic defenses.
Unknown are said to be able to convert Truestone into adamantium, a truly wondrous metal. They are constantly on the search for Truestone.