This deck is designed to quickly overwhelm your opponent with tons of zombies and tokens that do not stay in the graveyard for very long, then sacrifice them with Voldaren Pariah to win the game. The core cards are going to be Prized Amalgam and Relentless Dead, which are unfortunately the more financially pricey cards in the deck. You want to use cards like Collective Brutality and Haunted Dead to discard your Prized Amalgam as fodder, then quickly bring him back with Haunted Dead, Relentless Dead, or Gisa and Geralf for free by reviving other creatures.
Now lets talk tokens: Cryptbreaker is a nasty turn 1 creature that lets you put cards like Prized Amalgam in the graveyard, get cheap tokens out of it, and draw cards. Your Diregraf Colossus is less of a creature in normal ways, as you don't intend to be using him aggressively, but he'll constantly be pumping tokens into play with every zombie you cast. Get two on the field and it's a nightmare for your opponent to deal with, getting two tokens for every one zombie. Just remember that the zombie has to be CAST, not enter the battlefield, meaning that only playing from your hand or casting from the grave with Gisa and Geralf will trigger the effect.
Now that you've surely got a quick army of creatures that don't stay dead for long, it's time to try to discard your Voldaren Pariah and pay her madness cost. You can flip her as soon as she hits the battlefield, so sacrifice your Prized Amalgam, Haunted Dead and something cheap like Cryptbreaker or a token, and laugh as your opponent has to sacrifice their only means of defense, giving you a free ticket to bring your zombies back and take them out before they can recover!
With cards like Dark Salvation and Collective Brutality, you can get tons of value from them for really cheap. Dark Salvation is a powerful removal card that just gets stronger and stronger the more ahead you are. With 4 zombies on the field, it's a -4/-4 for only one mana! Talk about efficient. Collective Brutality lets you discard the cards you want out of your hand, like Prized Amalgam, Voldaren Pariah, or Haunted Dead, while reaping the benefits of cheap removal, hand control or just a little bit of extra life/damage. And lastly, Grasp of Darkness is cheap, effective removal that zaps those pesky Kalitas, Ulrich, Gisela, Avacyn and other game-changing cards before they can put out the hurt.
I've found that cheap burn cards seem to work pretty well against this deck, because you can bring your creatures back fairly often, but usually not every turn. The burn cards in Red right now are inexpensive and effective, they'll keep the good cards in your grave and off your field, so consider putting in Turn Aside or other counterspells if going up against a removal heavy deck.
Tips and advice are always appreciated! I'm still fairly new to building FDM standard decks, so there may be other suggestions or cards that work better. I know that Risen Executioner works great for this deck, but it's about to be out of standard so i didn't include it. Thanks!