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Tear Jerker: Looking for Group
Pretty much any character reaction to Krunch's death counts, but the final twist of the knife has to beBenny trying desperately to resurrect him, putting more power into the spell than anything we've seen from her before that point, and the resulting breakdown when she realizes that no matter how hard she tries, she cannot bring her father back.
Page 589. What starts as Richard being, well... Richard, becomes sad and incredibly disturbing by what he's implying. He doesn't want to kill innocent people anymore, and seems to believe that, by killing the Book of the Innocent, he won't have to. A very unsettling Out-of-Character Moment for the homicidal warlock.
Page 613 seems to confirm it. Richard is desperate to break the curse, having to frequently remind himself of what he was like before.