I straight up dont agree.
Where its necessary, sure. It isnt here. This is not something that needs to be rushed, and its palpably within the capabilities of the Ordo Lebes to raise wards around the homes of their members.
Takes them time, but they can do it just fine.
We're just here for the social connects , and to stack up extra successes on the ritual roll.
We dont have to go all out and show our every card in the process.
If TLF wasnt procing, you'd have an argument.
But TLF is procing. Between TLF and an Occult Excellency, we're likely to crack Legendary levels of success on a dice pool of 20 dice (Int 4 + Occult 5 + Excellency 9 + Stunt 2).
We dont need to do more.
My argument, point-by-point, and then I am going to sleep:
1) Is BSM useful here? Yes, because base difficulty is 7. Using BSM lowers it to 3, without it, it's 4.
2) Are there stakes here? Yes, this can in the future save someone's life. Even if the probability of this coming to pass is low, it's still important.
3) Does using BSM here cost us anything? Yes, the people present will learn that Molly works while wet and might draw some conclusions from it. It's doubtful they'll be able to discern the mechanisms behind it.
4) Does the information about BSM's aspect (without direct confirmation from us, and based on their speculation) harm us? Doubtful, because:
4.1) It only harms us if it leaks to our enemies. There might be spies here, but that's paranoic, these people gave us no reason to doubt them, and Rose of Autumn bought them a lot of credit and essentially vouched for them. They might also be caught and interrogated by our enemies. The stronger the wards are here, the less likely it is, even if indirectly. Even if they are caught, they can only offer their speculations.
4.2) We aren't likely to keep BSM's "we are better when wet" secret long term, if we are to use it in combat at all, unless we murder everyone we fight together with.
4.3) Our enemies learning of this aspect of our powers doesn't make it easier for them to stop us from using them. They can, what, blast us with fire to dry us off? Blasting us with fire was a viable strategy anyway.
So, we can potentially save someone's life at low possible (not a given) cost to us. I consider it reasonable to use BSM here.
Plus, I'll admit, I detest "keep all your secrets always, even when revealing them costs us nothing, and might help us" mindset. Tools are there to be used, not stashed away in fear of someone seeing them.
20 dice, difficulty 4… back-of-the-napkin math says 14 successes average, 16 because we're ignoring 1s. Granted, that's just an average, I'm not up to quickly calculating the probability ranges for different numbers, but still more than enough to make for a really nasty curse, especially with the rest of the coven adding their successes to the pool. And we'll probably have a qualitative bonus hitting above the normal weight class of that number of successes because we're fueling a curse with the essence of an Infernal Exalt, and the curse in question looks very thematically similar to a Kakuri Charm, which we have favored.
This is plenty to mess up the day of anyone who comes knocking with ill intent. Adding another 2 successes to the average by using BSM is not qualitatively different enough to reveal our hand.
"legendarity" of success seems to be graded at 5 successes (5-10-15), so ensuring we pass 15 successes could be important.