Greaves of the Empty Tomb is a Unique Boots. It can only be used by Necromancers.
Effect

How to get Greaves of the Empty Tomb
You can farm this unique from and Grigoire, The Galvanic Saint
. You can also use our handy Target Farming Tool to see which dungeon is best to farm this unique.Lord Zir
"The massive door to my family's crypt, which had taken a dozen men to close, was thrown open. Had I known the horrors to come I never would have set foot inside!" -The Ebon Pages, Canto I, Verse VII