"Thing_CopyMovement(sourcetid, targetid, reverse-toggle);"
-> Very simple isn't it? The command is actually very easy to explain, the thing with the targetid just copies the movement of the thing with the sourceid relative to it's angle!.
This means, two things pointing to 128 actually do exactly the same movement if "reverse-toggle" is 0! If it is 1, they do the same actions as they are mirrored on a line parallel to their angle.
If one thing points to 128 and another (exactly the opposite) and "reverse-toggle" is zero, the do the same actions as if the are mirrored in one point lying the middle of both of them. If "reverse-toggle" is one, they do exactly the same, just looking in opposite directions.
I hope this explanation is good enough to easily implement this feature as it won't be to hard, will it?
Some more specifications
You could add a third argument, telling the monsters what happens, if the sourceid or the targetid die (f.ex. "if target dies, nothing happens, if source dies, both die and so on)
This should also work for multiple instances of a new target object, so you could mirror 3 times the movement of one object in 3 different angles.
There are also different cases if objects are of a different nature, f.ex. if you mirror the Baron's movement with the behaviour of a Demon (means, speed and stuff must be copied from the source)
Give the command another argument to set a "movementratio" on the targetobject, so f.ex. the TARGET just moves 50% the way the SOURCE moves, if "movementratio" is "0.5"
