Rift magic is a rare depraved art. Not intended at all by the life stream, rift magic is the utilization of mana in order to rip open space at two locations based on the flow of the life stream, and temporarily 'knitting' the wound together to step through. Not easily bent, this power takes a strong magi, and after mere seconds, Eternia is more than set to right itself and 'correct' the mistake in itself.
Getting caught in a closing rift is generally unpleasant and potentially fatal.
Oftentimes used throughout history by assassins nameless virtue of their skill, rift magic leaves few left to teach it. Commonly, a fatal mistake made by a practicioner comes from an inadequate understanding of the location they wish to tear at. Rift magic utilizes an area's ambient mana flow in order to target it's location- Subtle shifts can often still be rectified, but many factors can cause this power to subtly shift- From the raising of a new building, to the felling of an ancient tree, or perhaps due to the longterm aboding and shifting of powerful magi, this ambience can change as subtly as the landscape.
Failing to make the proper connection can be lethal. If an incorrect tie is made, the manastream will default 'tear' into the void between stars. Given that most practicioners, particularly novices, can barely hold a portal open long enough for more than a handful of seconds, and the dialation of time within the void, once stepped through, an incorrect link will leave the practicioner never seen again, in the blink of an eye. This has been suspected as the cause of several 'mysterious disappearances' in the past, and leaves an excellent explaination beyond it's aberrant nature as to why it is an art best left alone: It's often deadly.
As a result, rift magic practicioners are limited by areas they have personally experienced, and must be incredibly sensitive to mana- Be it by training or by inherent skill. A visual of a location will do nothing for opening the way to a location: However, some perfected stealing memories or capturing samples from locations in order to utilize the power for nefarious purposes.
This does not mean this is the only way rift magic can be used- At immense levels of skill, magi can not only tear, but 'fold' space for themselves. While this 'folded space' is completely uninhabitable by a human- Much less big enough for one- Storing weapons and similar belongings within was a deadly tactic for the covert.