Mini star

Nazi ships could use non-fictinal Helium-3 as fuel. Non-fictinal Helium-3 is rare on Earth but it's thought to be greater in abundance on the Moon. Moon Nazis could

process moon regolith to make Helium-3. Helium-3 can be used as fuel on fusion reactor. Only down side is that fusin Helium-3 with itself or even with Deuterium requires very high temperatures.

Moon Nazis overcame this problem, but those shorcuts made inherently safe fusion reactor prone to hyper-accelerated chain reaction with catastrophic consequences. In normal operation reactor is perfectly safe, but with sufficient combat damage reactor could accelerate out of control. This would result reactor to become kind of a mini star.

It would melt the ship to form "star's" outer somewhat cooler surface:
Resuling fire ball like these but in smaller scale:

When "star" has consumed it's fuel and fusion reaction is dying, it first lose it's outer surface like giant solar flares:

Then collapsing into intsel and finally exploding:

After explosion all that remains is some gasses in near ships posiotion.
Result: