Originally Posted by
spirit of the wretch
Well, first and foremost Entomb acts as an additional Dredger, which is hugh on its own. Furthermore it should allow you to speed up your kill by tutoring for Dread Returns/Zealot/"that new carddraw Sphinx" if needed. It can help you recover quicker after your opponent "Mogg Fenantic"ed you. Postboard, it can get you that Ancient Grudge to force the Crypt activation without having to mill half of your bib.
The main reason I see to run this card is its flexibility. Against combo you get a faster kill, against aggro it assures that you hit your Dredgers, against everything else, well you're pretty much in a good shape anyway.