Breakdown Phenomenon are a Magicial Phenomena in the world of Trinity Seven.
Breakdown Phenomena occur when powerful magic goes out of control on a large scale. The results of these events are massive destruction, people within the effective range disintegrating, being pulled out of the world and becoming wraiths. The only way to resist this effect is to have sufficient magic, but this will only slow down the rate of disintegration rather than completely negate this action. The only way to stop it is with some form of powerful magic negation, or being cut off at the source with either the death of the mage who caused it, or their gaining control over the rampant power.
Each form of Breakdown Phenomena has a different sign, such as Arata's Black Sun, while Yui"s can make everyone(except Trinity Seven and Arata) sleep.