It doesn't seem right that a focused MDC energy weapon should deplete all of a character's SDC. The beam of energy will burn a hole through the character and continue on its way. I'm not even sure that hydrostatic shock will be a factor when using MD energy weapons against SDC bodies; I'll have to do some research. In any event, this system does not need any modifications to merge the worlds of MDC and SDC. The PV of a MD weapon is megaversal, applying to SDC armor and MDC armor alike. Even in MDC environments it is possible, even likely, for MD weapons to be used against SDC targets. This system will make the damage taken by SDC structures a good deal more realistic.
Example: An alien named Todd lands on Earth with a 1D6 MD laser pistol (PV: 21). Feeling a need to test the resilience of his new environment, he fires a few test rounds. The alien's first target is an unarmored woman (10 HP; 15 SDC; PR: 4) gawking at the spacecraft that landed on her front lawn. Todd fires at the woman, burning through and striking the house behind her with his unmodified damage roll of 3 MD. The damage applied to the woman is:
Damage = ( PR / PV ) * ( Unmod Dam ) = ( 4 / 21 ) * 3 MD = ( 4 / 21 ) * 300 SD = 57 SD
The woman is killed, but the laser is easily powerful enough to damage the house behind her. The first thing the beam encounters is a 10 cm thick brick wall (PR: 12). The beam acts like it is a 243 SD, PV: 17 attack, and the damage applied to the brick wall is:
Damage = ( PR / PV ) * ( Unmod Dam ) = ( 12 / 17 ) * 243 SD = 172 SD
The beam is now acting like a 71 SD, PV: 5 attack. It burns through the plaster wall (PR < 1) and a few items of furniture before coming to stop in the bricks of the opposite wall. Todd spends some time inspecting the woman's injuries and the brick wall while the neighbors call the police. After a few minutes, a SWAT team arrives in an armored vehicle (PR: 10). Todd performs another weapons test, firing at the new target. His laser cooks through the armor, with an unmodified damage roll of 2 MD. The damage applied to the vehicle armor is:
Damage = ( PR / PV ) * ( Unmod Dam ) = ( 10 / 21 ) * 200 SD = 95 SD
The beam, acting as a 105 SD, PV: 11 attack strikes the engine block. After penetrating about 2.5 cm of material, which disables the engine, the beam stops. Team members wearing riot armor (AR: 14; PR: 5; 180 SDC) jump out of the back and open fire on Todd. The MDC force field he wears is more than capable of absorbing the SD barage of gunfire, so Todd performs a third test by firing at a SWAT team member. The MD attack, with an unmodified damage roll of 4 MD, easily cuts through the armor, the wearer, and the back of the armor. Using the damage shortcut, which is very useful when MD weapons are used aginst SDC structures, we determine that the damage done to the SWAT member is:
Damage = ( PR / PV ) * ( Unmod Dam ) = ( 4 / 21 ) * 400 SD = 76 SD
The officer is killed by the laser. Todd fires again at another team member. This time he rolls an unmodified damage of 1 MD. The damage that member takes is:
Damage = ( PR / PV ) * ( Unmod Dam ) = ( 4 / 21 ) * 100 SD = 19 SD
This damage is enough to severely wound the officer, but he will probably survive. As a bonus, he'll be able to show people the armor with holes burned through the front and back, with a matching scar on his chest.