Board Thread:Lore Discussion/@comment-151.225.142.234-20140517150540/@comment-6941549-20140522122759

The reason the LDB survived was because Karliah fired her blood freezing arrow at you. After she gets you out of the Sanctum you release that you are in her debt. The poision was a advanced paralyisng poision that she was going to use on Mercer so she could hand him over to the guild and make him pay for what he had done.