I unfortunately didn't screen the previous sentences, but quintessence here is the answer that the rune powder can light up the entire Underdark when it explodes. Accordingly, the translation should reflect the emphasis on "Zerstörung" (as noun).
The Witch Bolt spell should be interrupted at obstacles (here stairs).
Missing text string.
A missing word here leads to the contradiction of righteous archdevils.... Correctly it must read: "[...] rechtschaffen bösen [...]".
https://forgottenrealms.fandom.com/wiki/Church_of_Shar --> Here one may orient oneself by the English original: "Sharrans". From this the correct German version is "Sharraner". If you thought that "Sharites" would be easier to gender, I have to disappoint you (der Sharit / die Sharitin vs. der Sharraner / die Sharranerin have the same result), so with "Sharraner" you can at least stick closer to the original.