The Dearg Dur - the origin story of the Waterford legend
The remains of the Dearg Dur (also called Dearg Due) are buried in Waterford at Strongbow’s Tree Her lustful yearning can only be satisfied on the day she died, so on the eve of her anniversary, locals gather and position rocks upon her grave so that she will not rise and take the blood of the innocent.
Source: irishcentral.com