This deck is all about putting cards into the graveyard and then using that against your enemies. In order to do that, you need cards to put other cards in the graveyard.
The simple way to do that is to destroy creatures with Casualties of War and Poison the Cup.
Another good card to use is Deathsprout to not only destroy a creature, but get a land out of it. You can use this land to get bigger spells out.
These bigger spells can even destroy more creatures at once, like Decree of Pain or In Garruk's Wake.
Now if you hadn't noticed, those big board wipes are expensive. Which is why Decree of Pain can be discarded for a much more reasonable cost to draw a card and still get rid of some smaller creatures.
Luckily, if you wait until late game, some of these cards even get better. For example, Avatar of Woe and Drag to the Underworld get cheaper and can cost as little as 2 mana. Plus if Ruinous Path is cast with 7 instead of 3, you also turn one of the many lands into a 4/4 creature.
The next method is through sacrifice. One thing that needs to get brought up is that if you have an opponent sacrifice a creature, they are one to choose that creature. So if they own a really small or useless creature, that is likely what will get sacrificed. But nothing is stopping you from sacrificing your useless creatures. Though, if they have only one creature left, that is what gets sacrificed. Barter in Blood, Smallpox, and Torment of Hailfire are great, straightforward cards to cut down the enemy numbers.
Now, those cards could be good for one time, but you could easily use Archfiend of Depravity or Clackbridge Troll for constant sacrifice unless your opponents want a giant Troll smacking them in the face.
Blighted Fen is also a sacrifice stick on a land, which is fun as many opponents tend to forget about your lands.
You could even sacrifice your own cards for some fun effects.
Attrition and Spark Harvest can be utilized to destroy specific creatures.
Izoni, Thousand-Eyed and Village Rites can be used to get some card draw that this deck sometimes really needs.
Eldrazi Conscription is a way to to get a big creature even bigger and Annihilator 2 which is the only way in this deck to sacrifice lands, artifacts, enchantments, or planeswalkers. Granted, there is no way to force what they sacrifice, but if their board is empty, they have to empty it even further.
The final reason to sacrifice is to receive bonuses every time you do it.
Grave Pact is a simple way to force an opponent to sacrifice a creature upon the loss of one of yours.
Moldervine Reclamation can be used for more much needed card draw.
Mazirek, Kraul Death Priest is a great card to set up for your final strike by getting all of your creatures bigger with every sacrifice.
If you feel like you can't spare a single card, there are a few ways to spare a few. Deadly Recluse is an early game card to deter attacks with its deathtouch, but becomes ample fodder when it is no longer needed.
card:Relentless Reveler causes all players to mill three cards which is at least six extra cards in the graveyard. Sac it as soon as you can.
Silumgar Assassin is an early game kill that once the kill has been activated, has decent pseudo evasion or can be used as a sacrifice later once he is done.
Izoni, Thousand-Eyed has already been discussed but when she enters, depending on how much you have been able to kill, she hands you a handful of tokens that can be used to sacrificed later. Do keep note that sacrificed tokens don't go into the graveyard, but they do count towards death triggers.
Garruk, Apex Predator, Garruk, Cursed Huntsman, and Garruk Relentless
need to be grouped together because they fall into almost all of the categories this deck uses individually. They all summon tokens for sacrificing, have ways to destroy creatures with extra benefits along with it, and their ults get your creatures much bigger and trample in order to help end the game in a spectacular attack. They each have their own things to keep each one unique from each other, so just read the cards to figure out the specifics, but they all have those three basic uses.
Autumnal Gloom
didn't really fit in any of the other categories, but it mills your own cards for those cards that require cards in your graveyard, then is a great field presence once it flips. Special note, it is also a fun card against counter decks. I have talked to some more professional players when I first started playing and they admitted that counter decks don't typically worry about enchantments so it will likely get onto the field fine. Then when it flips, hexproof will defend itself from most things that those decks may have in its sideboard. So it may not win a game singlehanded, but I'm not saying it won't.
Finally, there is one main type of card is a huge competitor against this deck. Indestructible. There are two ways to kill an indestructible creature: Sacrificing it or lowering its toughness to zero. Sacrifice is very prevalent in this deck, but as I have stated, it is hard to get an opponent to sacrifice a specific creature without killing everything else first. The other method is much more practical. Using a card like Dismember isn't a guaranteed kill, but it will take out most early to mid-game creatures for as low as 1 mana (if you don't mind paying some life).
