Rifts were dimensional tears that manifested through cracks in space itself. It was impossible to predict or accustom to the environment of a rift, since they tore apart several dimensions, creating access to diversely unique realms with climates and weather conditions never known to humans.
Some possessed uncanny conceptual laws tied to their worlds: dimensions where gravity flowed in spirals, where time moved backward, where thought itself became solid matter.
Of course, the more foreboding thing about rifts was the ranks of monsters that existed within them. They posed a level of uncertainty and danger of the unknown that should make every awakened not want to venture into such realms. However, the rewards were equal compensation for the vicious risks that they experienced.