User blog comment:PsychoWolf101/Dark Wisdom/@comment-32428067-20180928214537

The sacrifice is the dead player before you.. In Yggdrasil killed players simply disappeared and turned up at resurrection points, like Temples or Guild bases. But killing someone while using Dark wisdom enabled you to steal knowledge from the player, at a guess you had to forfeit getting a drop from the player though.

That´s how I understand it at least..