Aura is the latent Energy present in all space.
Just as flowing matter distributes itself to evenly fill a space, Energy will naturally spread as much as possible. This resulting 'atmosphere' of Energy is called Aura: Aura is usually composed of countless Elemental Energies that are either not under the right conditions or simply too inert to react with their environment or each other.
Aura at a distinct point in space is measured in Amplification (AMP). Where an AMP of 1.0 is the level at which the Elemental Energies have combined or decayed as much as they can on their own.
AMP increases whenever forces are applied to the Aura. This could be a continuous source like Osa from a flowing stream or a brief one like the Vir of a punch. Whatever the cause the result is more of a Root Energy being introduced then combining with the Aura, destabilising it. The degree to which AMP increases is determined by the amount of added Root Energy in relation to the amounts already present, so doubling the amounts would increase the AMP would to 2.0 but then adding the same amounts again would only put the AMP to 2.5.
Aura with a heightened Amplification means there are enough moving parts that it will shift and reconfigure even without further input, tending towards a state of lower AMP. It takes Aura only a few Turns to reach AMP 1.0 assuming there are no persistent causes of AMP increase. This is always the case: a higher AMP causes faster reactions and so drops proportionally quicker.
For Amplification to go below 1.0 requires that the Aura at a point in space has been displaced to somewhere else. This happens when strong forces pull the Aura away from a point, leaving behind a void that will be filled by surrounding Aura within Ticks unless prevented somehow.