User blog comment:Omega natsu2/Chapter 364: Tartarus Arc, Part 1: Immorality and Sinners, Predictions./@comment-4933386-20131214112639/@comment-1359322-20131214153739

Sounds plausible. The immorality and sin could very well refer to that. Sayla making Elfman injured/kill Lisanna does seem to fit that theme.