|Image From Clash of the Titans (1981).|
However, we're going to focus on a different idea for more unique magic items: monstrous magic items.
Monstrous magic items are certain monster parts that possess supernatural abilities that players can utilize. A great example of a monstrous magic item is medusa's head from Greek mythology. Even though it's no longer attached to her body, the head still possesses the ability to petrify individuals.
When designing a monstrous magic item, study the monster you will be using and figure out what part you will be working with and what power that part will possess. Continuing with the medusa's head example, its pretty easy to say that her head would allow the player to use the creature's petrifying gaze ability (turn to stone permanently, 30 feet, Fortitude DC 16 negates), as a standard action (or once per day, whichever you prefer).
You should also consider how difficult it will be for the characters to obtain the part when determine its supernatural properties. For example, let's say you decide that the scales of a red dragon can grant a character a resistance to fire-based attacks and spells, with the size of the scale determining how much resistance is granted. So, players who might want a scale with a better resistance factor will have to hunt down bigger and stronger red dragons to obtain those scales.
Finally, you might also add a "gross" factor to the monstrous magic items since you are basically using a most likely dead creature's body part. For example, let's say you allow players to drink a troll's blood, it working like a potion of cure light wounds. However, you might require them to make a Fortitude save while doing it. Success allows the player to receive the healing effect, but failure causes them to regurgitate the blood before the effect can work. This also has the side-effect of limiting the use of troll's blood in this way because its not as reliable as a potion of cure light wounds, but gives the player's an option when they are desperate and don't have a potion available to them.
Monstrous magic items can add an interesting element to your game and help make more unique magic items, which is always a good thing in my book. Due to all the monsters at a GM's disposal, the possibilities are endless.