From the Back Cover:
You have all the time in the world - and now you don't.
The final most dangerous frontier lies not in space, but in time! At last, the dimension of Time is open to those few wizards who would risk everything – even their existence - to visit ancient and forgotten lands, or see the unbelievable wonders and horrors of the future. These few wizards are Chronomancers, and this optional 96-page AD&D® game accessory reveals the secrets of their lives. New spells, new powers, and new realms – As well as terrifying monsters – are brought to light in this stunning work. Take time to study the mysteries of chonomancy – before someone else takes that time from you.