The worlds and planes known to even the most enlightened beings and gods comprise only one facet of the whole of existence. Unbeknownst to most of existence, the Whole is comprised of two opposed spheres: Existence and Non-Existence. (As they are called from the perspective of the Extant who are aware of them. Those incomprehensible beings of Non-Existence prefer to think of them in terms of concepts closer to fuel and fire, though those material concepts are far removed from the comprehension of the Non-Extant.)
Non-Existence contains of many of the same elements that comprise Existence. Specifically, magical energy has a Non-Extant parallel, chaos energy. Chaos energy functions much as magic in both spheres. However, because of its non-extant nature, when it is utilized within Existence, it tends to reduce inert matter to the basest of elements, and to corrupt living matter. That is Chaositech.
I've extended the concept a bit. Since Non-Existence is not governed by time, chaos energy reverberates along the time line as well. In small amounts, it only affects a period of seconds or less in both directions. But greater manifestations will affect the recent and possibly distant past and future, mutating that as well.
IMC, the PCs live on a fiercely contested world, and there are those extant beings who are aligned with the forces of Non-Existence, and work to bring about the consumption of this world. Presently the effects are relatively minor. But that's going to change.