I said I would whine here when I thought there were balance concerns and whine I will!
So there is an item, explodifier.
It quadruples explosive damage.
This seems to apply to the torpedo launcher secondary.
Now, I'm not absolutely certain of this, as it's possible I just had that much damage naturally (I did end up getting the quad crit thing as well).
Still, taking out half of Terminus' health in a single shot? That makes you wonder real hard. Makes you question things, things like "Is this perhaps a bit more powerful than it ought to be?"
Attachments are, in order, start of floor save, pre-terminus save, pre-terminus screenshot, post terminus screenshot.
Take a look at time elapsed on the screenshots