[mr beer]

What does "pierce" stars mean? Penetrating a star to some extent would seem considerably less powerful than destroying it.

I saw a table online somewhere which had the power output for a whole bunch of things, from nuclear weapons of various sizes, comet/asteroid impacts, Death Star laser, through the Big Bang. No idea where it is, but something like that should give the power requirements for any massive weapon.

You can probably scale between one of the human sized weapons to your Star Smashing beam from the power requirements to calculate the number of d6 damage it does.