1 This is a (EM style) magic wall. It gets activated for a limited
2 time by rocks or gems that fall on it. Objects falling though
3 it will be changed to other objects. After it has stopped running,
4 it cannot be activated again.
6 The duration is expressed in seconds. A duration of zero will let the wall
7 run forever. All regular magic walls run together; however, BD style magic
8 walls have a separate counter.