Retrodivination is the use of divination magic to fix future events in accordance with the desires of the retrodiviner. (I.e. the diviner's will is imposed on the future, instead of the diviner learning what the future will be passively. This latter concept is now thought to be theoretically impossible anyway, but was once considered a goal in developing future-divination magic, before the whole field fell into disrepute.)
Methods of retrodivination have apparently been lost since the Catastrophe, and were in any case highly guarded state secrets before then; many modern scholars have questioned if practical retrodivination was ever employed.