I found the sound for Dark Energon (in Transformers Prime), and isolated it if anyone wants to use the sound for stuff.

I imagine y'all have some figures out there improvised or outright made with Dark Energon in mind, maybe even a Unicron (or like me, a Herald of Unicron) figure you wanna use the sound for. I noticed nobody had it anywhere, so here it is.

It's also from the "Darkness Rising" episode, since the spot I got the sound was right before Megatron says "RISE, MY ARMY!". I didn't even have to mess with the soundtrack or layering tools, it's a perfectly quiet moment where I could hear the sound and make a (mostly) seamless loop.