These hammers are normally found as normal blacksmith hammers but with extensive runework on their sides giving a hint to their special nature.
These grant the wielder the potential to force a captive spirit into a metal object.
While holding the hammer, the wielder becomes capable of touching objects in the spirit realm, allowing them to grapple such beings. Whether the bearer is strong enough to impose their will is another matter entirely, and it may be that strength of will avails more in that realm than pure brawn. Note that the spirit realm is also better able to interact with the wielder as well.
Once a spirit has been seized, the process of forcing the spirit by literally hammering them in starts. This too is a battle of wills between the smith and spirit, and is affected by the quality of the item being used as a vessel. Depending on the power levels and the relationship between the spirit and smith, the process could take a very long time even if successful.
After embedding spirit in the object, the smith may impose a pact - lend their power in some manner to the item for a fixed period of time - or condition, upon which they gain their freedom. The terms of this condition are entirely between the spirit and the smith, and is strongly binding on the spirit. Once trapped, it is unlikely for them to escape without assistance, though a poor bargain increases the odds.
Alternately, the trapped spirit may be used as a simple manna battery for powering specific enchantments placed upon the item. Depending on the game-world metaphysics, the spirit may or may not provide an eternal source of power. This type of use is greatly offensive to the trapped spirit, and it will constantly seek out escape, though the draining of it's power makes escape remote.
There is nothing against the smith using a willing spirit as part of this process, in which case everything becomes much easier. Smiths with necromantic knowledge may be able to work with the spirits of the recently departed.
Various variants of this hammer may be found which are predisposed to different spirit types and may provide additional options when dealing with them.
These are not unique items, but a class of item. They are created through producing a hammer of fine quality, and the application of magical Runes of power. Knowledge of the runes is close held, and the skill to form them rare.
Playing with the realm of spirits is always hazardous, and the Smith should make sure to take precautions to prevent outside influence such as protective circles, wards and even physical barriers. The action of pounding a spirit into an object will not go without notice to those attuned to such things, though this will depend on the nature of the spirit. Attention may be drawn from the infernal, the divine, the sorcerous and other things best not mentioned.
- The spirit in the item may have friends, allies or even enemies which may seek them out.
- A smith has had this item stolen by those seeking to do battle with spirit enemies. Some critical dingus needs fabricated, but this hammer must be recovered. The thief could very well be a powerful hero who believes the end justifies the means.
- A spirit used as a power source happens to know a critical secret. It is possible that the hammer can be used to _remove_ a spirit as easily as to imbed one.
- Enemies now seem to have access to larger numbers of magic items then one would expect, though many of those recovered are surprisingly resistant and contrary. It turns out that many common people have been used to power them. Do the PCs keep these items, or do they seek to release their captive spirits?