User blog:Mr. Bambu/D&D Homebrew Calc: Soul Bomb

Premise
Found the Soul Magus Homebrew class. I rather like the premise of it, so I figured I'd add it as an NPC and thus needed some lore for its arrival. However, it came with some lore, funnily enough. See here for details.

"You see, there's one thing you forgot: Soul Bomb."

- Alan Sanders, Human Soul Magus, before the Goblin Kingdom was suddenly and inexplicably replaced with a crater

Let's calc it. In my own verse, let's assume it was performed by a Magister, a unique chosen of the gods of magic, and thus a nearly unparalleled caster.

Calc
According to my map of the small kingdom the party recently cleared, it was about 537 meters in radius, and should be roughly circular in terms of land area.

We will assume the crater is 1/10th as deep as it is wide, so our half-ellipsoid has the measurements of 537, 537, and 53.7 meters.

This equates to 6.49e7 m^3 of vaporized stone. Density of stone is 2750 kg/m^3, so mass is 1.785e11 kg. 6077872 J/kg is our value.

Energy = 1.085e18 Joules, or 259.32 Megatons of TNT, Mountain level.

However, that's just the crater. The city itself was destroyed, as was the mountain containing it.

We will assume this mountain has a base at least 2.5x the radius of the city, making it 1342.5 m in length. Height, we could assume minimum of 609 meters- it is taller than surrounding mountains, but not so much that it is impossible to say "this is probably baseline mountain".

The volume of stone is now 3.66e8 meters cubed. Multiply by density to get 2750 kg/m^3, and we have 1.007e12 kg. We get 6.117e18 Joules, or 1.46 Gigatons of TNT, or Small Island level.

Tally
Alan Sanders Vaporizes the Goblins: 1.72 Gigatons of TNT, Small Island level

Scales to what are essentially the strongest mortals before becoming gods. Vaerun might, of the newer PCs, but aside from that, I don't think so.