I followed his path around Harlan's Lament in Droughtlands and recorded it with Map Extension (great add-on!). The gem symbols on my uploaded screenshot mark his circuit around the two log bridges.
Several "Neglected Sacrifice" skeleton enemies will circle a pathway between the two log bridges over the tar north of Harlan's Lament when the Forgotten Sacrifice is present.
If you see a Neglected, search along their path (or type /tar Forgot) for the Forgotten Sacrifice itself.