Temporal Magic

Temporal magic is the school of magic that studies time manipulation and time travel. It is a secretive and rare school of magic, requiring much magical power, while mages have qualms with the idea of altering the natural course of events. 
Time travel uses teleportation magic as a spatiotemporal means to manipulate location.       
Mages skilled in the temporal arts are known as time mages, temporal mages, chronomancers, time travelers, and clockworkers.   
Also: Time magic or Chron
Temporal Spell Types:
Event Manipulation – To create a change in probabilities. Though this change lasts for just a moment, it has a profound effect on a single event. Also: Probability manipulation     
Time Manipulation – The speeding or slowing of time for everything other than the caster, i.e. the world around him or her can be sped up to high speeds or slowed down to a crawl. Time for their surroundings can also be stopped. Rewind will rewind the world backwards in time, at various speeds.       
Speed Magic – The speeding or slowing of time for objects, individuals or processes. This includes the caster. Speed magic is most often found in magical items or enchantments, and can be casted with spells; fast travel, boots and bracers of speed, shackles of slowing, haste spells, slow spells, etc. The speed of magic casting can also be altered, as well as the duration of a spell. Permanency magic makes spells permanent, yet can be dispelled with anti-magic. Temporal stasis freezes the time for an object or individual, suspended in animation.             
Scrying – Magic that allows the user to see into an area or location, or allows them to peer into a different time. Scrying devices, i.e. crystal balls or scrying pools, and material mediums are used that are enchanted with such spatiotemporal magic. Projections of light can also be used, or clairvoyance spells. Scrying can be blocked with anti-magic or some prismatic gemstones.
Time Warp – The creation of a gravitational warphole that brings people and objects it comes in contact with to different points in time, forwards or backwards, and to a spontaneous location. 
Time Travel – The movement through time, or space and time. Time travel can be done into the past, present, or future. Altering the past does not affect the present for the caster, and will instead create new reality planes, or alternate realities, while the portals that lead backwards in time are limited in duration, before people and objects begin to disappear and the portals cease to exist. Only by closing the portal, which cannot be created again to get back to the present time, can a traveler remain in the past plane safely. Time travel into the future can be freely done, as the caster or traveler can return to his or her original location and time, without any collapse or affect on the present. Once a portal to the future is closed, however, traveling back to the present will collapse the plane if a portal is kept open. The psionic time travel method is another way to move through space and time.
*Time-travel into the past collapses and creates alternate reality planes, in what is known as an event collapse. Once time travel is done into the past, it cannot be done again to the same plane. Scrying into the past is also no longer possible into the same reality after it vanishes. Future time travel is freely exploited, and to return so long as the traveler's original location is marked. 
**Gravity warps and time warps can wipe out entire armies, cities, and civs, by relocating them or placing them in other times, or with powerful singularity magic.