So here is how
@DragonParadox is ruling on GSNF. As in this is how he explained and rolled it.
Say Bob has 15 soak. Molly attacks and rolls and does, say, 5 agg damage. Bob soaks agg, so he then rolls his entire 15 soak and gets 4 sux, meaning Molly does 1 dmg.
As it is a successful damage, she spends reflexively spends 1 Essence for GSNF and does 5 agg damage, no rolls needed. Bob then, again, rolls his entire 15 Soak again against the 5 agg damage, ignoring the result of the previous sux. He rolls soak and gets 5 sux. So GSNF does no damage.
So Bob rolls soak twice, once against the normal attack that did damage and once against GSNF.
Which I think is against the intent of the charm. As per the bolded part, the radiation erupts, literally from within the character's wounds and internal injuries should not be soaked. At the barest minimum, Armor soak should not apply as it is completely bypassing armor.
I agree that this damage really should not be soaked separately and given how (a) precious Essence is, (b) 3 Dot Charm, (c) Mechanics and Flavor text, (d) Most high level characters can soak Agg, (e) The Solar and Sidereal versions add to damage rolls and not separate rolls, it is not intended to and should not be soak able.
Here is the Solar and Sidereal charms.
So both the Solar and Sideral versions add to Damage roll rather than do damage seperately. The Solar version is also a 3 DOT charm.
@DragonParadox To add to the discussion, GSNF does not say add to roll because it specifically requests you to do damage.
In the Solar version the soak roll is still pending and the charm Adds to that roll.
But GSNF is different in that it requests you to do at least 1 dmg. Meaning the Soak roll has already been defeated.
That is the difference. It requires you to defeat the soak roll to do agg damage. Because it makes no sense otherwise.
There is literally no damage adder charm that requires you to roll soak twice for different damage. Literally every charm is concluded in one roll.
The Solar version is a do not loose charm whereas the Infernal version is a win harder charm, aimed at regenerators like Lunars.
Because, due to the prohibitive Essence cost, rolling Soak twice for attacks with GSNF is a massive nerf as no other charm has this treatment.