BOTTOM LINE UP FRONT: Fire Knight Stage 3 is the most energy efficient method for completing dungeon diver events.

So, for 8 energy per run in the fire knight dungeon stage 3, we get the values circled in green (plus green shards, ancient shards, and brews). For almost double the energy, starting around stage 13, we get the values circled in red.

So, for almost double the energy (and truly double at 16 energy cost) we don't get double the points from the gear drops.

From my trial runs, 130 energy spend on stage 3 (about 16) runs, I averaged 100 points. On stage 15, 130 energy spent (about 11 runs) I averaged around 80 points.  Both stages have about an equal chance to drop non-gear garbage, so it’s better to do more runs on stage 3. I frequently got epic and occasionally got legendary drops on stage 3. I RARELY got epic gear drops, and even MORE RARELY were the 6 star gear drops.

I got more legendary gear on stage 3 than stage 15! Additionally, I got more ancient shards on stage three than stage 15

Unless someone can tell me what the drop rates are like, and the average points earned for 130 energy farming Fire Knight on higher difficulties averaging more than 100 points, this is my theory.

I tested other dungeons at stage 3 and the highest stages I could do. They all dropped more common and uncommon gear compared to Fire Knight.

This is just another example of how Plarium is either

1. Terrible at balancing games and creating point distributions based on their game balance.

Or

2. Balancing the game to give newer players the advantage so they think spending money will be profitable. Aka, Plarium designs the game to sucker you in, once your hooked you keep spending money because you already invested so far, you feel the need to keep going.