Just a funny (and little cheatty) bug in WBC1 :
When you transform 4 wisps into an old Wisp, you can right click on the floor just after clicking the transform button, the 4 Wisps start to fuzion but stop the action in order to move.
If you quickly reclick on the transform button after the order to move, they will do a strange movement and fuzion again at the place you order them to go.
Eventually, if your timing is perfect, two Old wisps will be made. One at the first place they tried to transform, and one other at the ground order targeted location.
It let you to save the time and resource needed to build another 4 Wisps, nevertheless it costs 200 crystal instead of 100 because you used the ability twice.