Allomancy is one of the three magic systems in the Mistborn fantasy novel trilogy, and is the most prominent. People capable of Allomancy are known as Allomancers. Allomancers have the ability to “burn” (or use) metals, in order to fuel a variety of physical and mental enhancements and abilities. For an additional burst of power, they may flare, or burn their metal especially quickly, consuming it at an accelerated rate, but gaining greater benefits in return. A person who can only burn one metal is known as a Misting. If a person is born with the ability to burn more than one metal, they can burn all Allomantic metals, and are known as Mistborn.

Feruchemy is the second magic system in the series. Feruchemy works differently from the other magics. While an Allomancer burns metal to gain power, a Feruchemist can use these sames metals as holding units, or minds, to store up their own power. Basically, depending on the metal, a Feruchemist can become worse at something in exchange to be equally better in the future. No power is gained or lost.
The major strength of Feruchemy versus Allomancy is the speed at which one can access its power. While a Feruchemist must provide the power for the magic from himself, storing it over time, an Allomancer can simply consume metals to power the magic. However, an Allomancer has limits to how much power they can draw at once; a Feruchemist can draw out the power of the metalmind with virtually no upper limit, exhausting it in one massive burst if they so choose. For instance, a Feruchemist tapping a pewtermind can be far, far stronger than even a very powerful Mistborn burning pewter, if only for a short time.
Feruchemy is in the genes of the Terris people.

Hemalurgy is the third magic system in the Mistborn Series. To use Hemalurgy, a metal spike must be driven through the heart of someone. Then the spike is taken and stabbed into a body of another person, the spot depending on the power transferred. The prefered method is to stab it directly through the heart into the other person, as the longer it is left out of the body the more power is lost. While Allomancy is the art of Preservation and Feruchemy is the art of balance, Hemalurgy is the art of Ruin, as the transfer of power destroys some of it. Allomancy creates power, and Feruchemy does not destroy or create. Having a hemalurgic enhancement makes one susceptible to Ruin’s influence (e.g. Zane, to whom Ruin could directly communicate; and Vin, who occasionally heard Ruin’s voice in her head, though she mistook it for memories of her brother, Reen) or even to his control (e.g. Steel Inquisitors in books two and three). This, along with the fact that kandra and koloss, both of which are hemalurgically enhanced, can be controlled by Soothing, leads to the further speculation that hemalurgic enhancement of any kind makes one susceptible to being controlled by an outside force.

The Fall of the Central Dominance