Reverse jump through gate [872]
-------------------------------
Usage:  USE 872 <gate> [key]

Required aura:  two points for each 50 weight
Required item:  none
Time to cast:   one day

Gates were long thought to be one way portals through space.
Most mages believed that returning to the starting location
required a second gate or a conventional journey.

However, it is possible to jump back to a gate from the gate's
destination.  Reversing the direction of teleportation is
difficult, so the jump requires twice as much aura as a
forward jump.

As with a conventional jump, the mage must know the gate's
entity number as well as the key, if necessary.