Originally Posted by
Yogg-Saron, God of Death
I didn't read through this thread, but judging by the small lightning still emanating from Ra-Den, and Lei Shen apparently having taken his heart, it seems likely that using Ra-Den's freshly harvested heart was what gave Lei Shen his thunder powers in the first place, while the other flesh might've been used to create The Divine Bell.
I mean, I haven't seen a Mogu with the ability to use lightning before, and yet here we have a Titanic creature, whose heart has been ripped out. If we pair that up with the knowledge that some Pantheon have been said to possess powers over certain elements, it doesn't seem too out-of-place that at the time of battle, Lei Shen was a normal Mogu (as far as a Mogu that strong can be normal) and earned his title of Thunder King and the powers after defeating Ra-Den?