Cards like this are often overlooked, but Wizards of the Coast did print a similar card in the past -- Demonic Tutor. Now it's a staple card of the Vintage format, but it is illegal in Modern. Now we have an alternative spell with an Undergrowth mechanic, which can be used for great effect in the following Modern decks.
The entire plan of this deck relies on having as many copies of Death's Shadow in play as possible. With the help of Mausoleum Secrets and only one creature in your graveyard you will be able to search your library for Death's Shadow, put it in your hand and potentially play it on the same turn.
The same strategy can be applied in the Living End decks that can help you search for the Living End sorcery. Since this deck can quickly put many cycled creatures into your graveyard, finding what you need will not be a problem.