Magic Element (魔素 Maso, localized as Seithr), in BlazBlue is a substance that covers the planet. It can neither be seen nor smelled. In small doses, Magic Element is harmless to humans, but in larger quantities can carry very detrimental effects; one can become addicted and their body will deteriorate. During the Great Dark War, the Black Beast spread this Magic Element all over the world, in order to operate. Because of this, the Six Heroes taught the humans the secrets of the "Magus" in order to defeat the beast. Magic Formula was created to consume the Magic Element and utilize it as a source of energy.
Surprisingly, small amounts of Magic Element might have favorable effects on the world, as in the deeps of First Area, the Magic Element leaking from the Kiln was neutralizing radiation and other harmful substances, clearing the air of any pollution. However, higher concentrations float around in clusters of toxic fog.
It can be categorized as a particle-type phenomenon.
When one uses Magic Formula, they draw Magic Element out of the environment to power it but there is only so much Magic Element in a given area. If one were to use up all of this Magic Element, they would have to wait a while for it to replenish. Some people can perform Magic Formula with less Magic Element than others. After the Great Dark War, a lot of humans and animals became tainted with the Magic Element and died off, save for the Kaka tribe. Humans were forced to move to high-altitude areas and create cities there. This is where the Hierarchical Cities come from.
The Magic Element was present in the atmosphere before the Black Beast appeared, but since only conjurers and mediums had uses for it, the public was unaware of its existence. Later it was also used by Drive-Union in a similar manner as Magic Formula.
It is believed that all living things are made of Magic Element and humans can even be broken down to Magic Element either by the "Soul Eater" or when Drive-Unions progress to Phase Six; Acht being a prime example.
In the end, the world has been depleted of Magic Element due to Bang Shishigami having activated Kushinada's Lynchpin. As the exact properties of Tenjō Amanohokosaka's Soul remain unexplained, it is unknown for how long this state will remain.
- "Seithr" is derived from Seiðr, an Old Norse term for a type of sorcery or witchcraft.