Since my skill level of Super Transformation is only 1, so my skill duration and skill cold down are both 60 sec. Therefore, I always recast Super Transformation by keep pushing hotkey to Super Transformation again when the duration is almost over or the skill animation after I leave Super Transformation is over. However, I found that Super Transformation will cost not only 1 magic rock if I recast Super Transformation by keep pushing hotkey. For example, in the following video, the Super Transformation cost 9 magic rocks if I recast Super Transformation by keep pushing hotkey when the char casts Dragon Strike.
I noticed some time ago that super transformation sometimes use more than one rock too. I tried it out myself to find out. I have it as a non-macro and it's the same for me. The longer I hold the button, the more rocks the skill will use up it seems. Even when I do a quick click it will sometimes use 2 rocks instead of 1.