The Deck

This has got to be my favorite historic deck I've ever made. The center of the deck is possibly my favorite card ever: The Scarab God.

It's resistant to removal, has a big body, and the ability to ressurect creatures from the graveyard as 4/4s (called eternalizing) is incredible, especially with creautures that benifit from the 4/4 body.

These are both are both powerful creatures on their own, but as a 4/4, they are game winning. Dreadhorde Arcanist as a 4/4 can recast any instant or sorcery in the deck, including Baleful Mastery, Kolaghan's Command, and Prismari Command. An eternalized Dreadhorde Butcher gets to deal 4 damage to any target when it dies, which is capeable of removing nearly anything or finishing off your opponent. It also has haste which is pretty nice.

Now the obvious problem in this deck is getting The Scarab God on the battlefield without losing. Both Arcanist and Butcher help with that, but it's nowhere near enough to deal with the aggro and midrange decks in historic. Thats where, well, the rest of the deck comes in. Let's start with the other creatures.

Hostage Taker is a powerful removal spell that provides a blocker and can be brought back with The Scarab God. Mire Triton gains life, has deathtouch making it an extremely good chump-blocker, and fills our graveyard. Stitcher's Supplier is the ultimate way to fill a graveyard in Historic, plus it can chump and makes for a good creature to eternalize.

The other part of reaching the late game where we can dominate with The Scarab God is messing with what our opponent is doing. For this, the deck runs poweful, interactive instants and sorceries.

These are the deck's 1 mana instant and sorceries, which can be flashed-back with a non-eternalized Dreadhorde Arcanist. Brainstorm is some of the best card filtering in the game, and it works well with mill effects like Tymaret Calls the Dead, Mire Triton, and Stitcher's Supplier, which can remove unwanted cards you put on the top of your library. Inquisition of Kozilek and Thoughtseize are the best hand-hate spells in Magic. They can deal with counterspells, removal, early and late game threats, basically anything. For the price of one mana you get to take away the best card in your opponents hand. Spikefield Hazard is mostly a land, but it is great against creatures with 1 power or that you want to exile. (Kroxa, Titan of Death's Hunger perhaps?)

These are the more expensive instants and sorceries, which can only be flashed-back with a 4/4 Dreadhorde Arcanist. Kolaghan's Command is a versatile spell which can return The Scarab God to your hand and remove creatures or artifacts. Prismari Command can filter through cards and allow you to cast The Scarab God on turn four with its treasure token. Baleful Mastery is just an unconditional exiling removal spell.

The last nonland card in the deck is Tymaret Calls the Dead, which fills the graveyard, creates blockers, and synergizises with zombies (nearly every creature in the deck is a zombie!).

Play Reccomendations

Keep hands with 3-5 lands, or 2 lands and and a Brainstorm to find the third. Look at your hand and make sure it does something in the early game, otherwise your opponent will be steamrolling you by turn-5. Thoughtseize and Inquisition of Kozilek are the best turn-1 plays, and you want a solid turn-2 or turn-3 play. Having the Scarab God in hand is not nessesary, the decks runs a lot of card filtering and functions well without the Scarab God. You'll find him eventually.

Don't be afriad to chump block with creatures. If you can play a Scarab God on turn five with a reasonable life total, you should be in good shape, plus, those creatures just end up in the graveyard which is exactly where you want them to be.

If you can play Dreadhorde Arcanist on turn-2, do it. The earlier you can start flashing-back spells the better. 

Congrats on getting to the end! I spent a lot of time designing, playtesting, and iterating on this deck to make it powerful and fun. I really hope you enjoy it :)