I was judging Game Day, so I had no opportunity to face the Hydra. Those who fought it seemed to be having fun, and after buying a Hydra deck and dueling it with my various sixty-card decks, I can see why. The rules of facing the Hydra are different enough that it's unique both in play and in deck-building. New formats are always fun to explore, so let's get exploring!

Treating the Hydra like An RPG Boss

The Hydra is a boss wrapped in a mystery inside an enigma inside a deck. The object of the facing the Hydra is to render it headless—controlling no Head creature cards—at the end of any turn. There are eighteen Heads in the sixty-card deck:

7 Elite Heads – Four of these are 0/6s, and three of these are 0/8s. Hydra heads deal 1 damage when they're on the battlefield, but Elite Heads deal 2, so they're rough regardless of the rest of the board state. Each of them grants you life and lets you draw a card when leaving the battlefield. The most sinister of these is probably Savage Vigor Head, which casts an extra card from the Hydra's library on the Hydra's end step.

When a Head leaves the battlefield, the Hydra reveals its next two cards, bins the sorceries, and puts the Heads on the battlefield. With eighteen Heads and forty-two sorceries, odds are slightly under even for revealing a Head. In my experience, dueling on Easy (two Heads on the first turn) usually means killing five to eight Heads throughout the game; I assume harder difficulty levels scale similarly.

Here are the sorceries:

5 Disorienting Glower – Players can't cast spells until the Hydra's next turn. It's a tempo play that, given the deck, doubles as burn.

4 Distract the Hydra – Players have the option of sacrificing a creature and tapping a Head (tapped Heads don't deal damage on turns) or losing 3 life. This one's unpleasant.

4 Grown from the Stump – It either reanimates two Hydra Heads or mills the library until it finds a Head to put on the battlefield.

3 Neck Tangle – It Frost Breaths two Heads if there are five or more Heads on the field; otherwise, it casts the top card of the Hydra deck. So, it's either great or terrible.

4 Noxious Hydra Breath – It deals either 5 damage to each player or destroys each tapped non-Head creature. This is the only card that can punish all-out attacks, though in my games, it was harsher as a burn spell, enabling turn-five kills on Easy.

2 Strike the Weak Spot – It destroys a Head and gives the Hydra an extra turn if it destroyed an Elite head. This is mostly upside to non-Hydra players.

5 Swallow the Hero Whole – This exiles one of your creatures, either temporarily if you can kill a Head on your next turn or permanently if you can't. It's a relief to see one of these wasted early, but it can destroy you midgame if you're already stumbling.

4 Torn Between Heads – This Frost Breaths two Heads and deals 5 damage to each player.

6 Unified Lunge – This deals damage equal to the number of Heads on the battlefield.

So, the deck has a lot of 0/3s, a lot of damage, a lot of extra turns, and some wobbly creature removal. That's how the boss fights, so how will you fight back? Like with most RPGs, I see two main approaches.

Hack-and-Slash

In addition to being a flavor match against a Hydra, hack-and-slash is time-honored and generally competent. Most of what you will want is creatures with at least 3 power so that you only need one creature to kill a Head. There are about a hundred creatures with 3 power or more for 2 mana or less, including:

Blind Creeper – Don't play spells until your second main phase.

Death's Shadow – The Hydra loves to eat your life total, so why not take advantage of that?

Drooling Ogre – The Hydra never casts artifacts . . . 

Loxodon Peacekeeper –  . . . will never have the lowest life total because it has none . . . 

Oona's Prowler –  . . . and can't discard.

Tempting Wurm – It took eleven years, but Tempting Wurm is now the king of a format.

Just with those creatures, an aggro deck with loads of removal should work. Something like this:

"Hack a Hydra"

• Creatures (23)
• 4 Accorder Paladin
• 4 Oona's Prowler
• 4 Loxodon Peacekeeper
• 4 Plaguebearer
• 4 Markov Patrician
• 3 Abattoir Ghoul

• Spells (13)
• 4 Porphyry Nodes
• 4 Killing Glare
• 3 Krovikan Rot
• 2 Tribute to Hunger

• Lands (24)
• 14 Swamp
• 10 Plains

Buy This Deck

This deck is straightforward. Send creatures at the Hydra Heads and removal spells at the Elite Heads. In my experience, life-gain from killing a Hydra Head is vital to mounting a comeback against all the early burn, so the sooner you start killing Heads, the better your chances of winning.

The rest of the deck centers around Heads having both power and converted mana cost of 0, allowing you to play a number of spells you might not otherwise. Porphyry Nodes will kill a Head like clockwork every turn, and Krovikan Rot and are Plaguebearer repeatable removal.

The Mage Approach

If you're more of a spell caster than a fighter, your deck will take a different tack. There are a bunch of rules that make the format unique:

1. The game only ends when there are no Heads on the battlefield. Apart from Darksteel Reactor–type effects, there aren't other win conditions available. This is in part because . . . 
2. The Hydra never has a hand, it can't draw or discard cards, and it therefore never draws from an empty library.
3. "If a Head would move to any zone other than the graveyard, instead put it into the Hydra's graveyard." This means that Aether Adept and Doom Blade are equally deadly. Strangely, attempting to send a Head to a zone it could go to will also kill it (e.g. Time Ebb or Warp World).
4. Direct damage or life-loss pointed at the Hydra is redirected to a single Head. Lava Axe can finally kill creatures, in a way the cinder hatchet never could.

These rules and other crafty happenings open up another odd suite of cards, such as:

Energy Storm – Damage-dealing sorceries—Noxious Hydra Breath, Torn Between Heads, and Unified Lunge—are over a quarter of the deck. Energy Storm's cumulative upkeep is almost certainly worth blanking those.

Spirit of Resistance – The Hydra can't handle magical orbs.

Mark of Eviction – Or rent payments.

Empty the Catacombs – The Hydra would love to put its heads in its hand, but it cannot do so.

An-Zerrin Ruins – Name Head for the creature type, find some way to tap down the Heads, and save yourself loads of life. You still have to kill the Heads, but at least they're not hurting you as much. Juntu Stakes is similar if you're not a fan of red and/or Homelands. (The Hydra never expected to fight in Ulgrotha! Bwahaha!)

Many of the cards I just mentioned are enchantments, which makes sense, as there are a lot of old corner-case enchantments that hurt the Hydra while it watches helplessly. Your Auras are safe; the only things the Hydra knows to aim for are life totals and creatures. So, instead of hacking off heads with weaponry, why not try to enchant the Hydra to death?

"Mystical Hydra Death"

• Spells (36)
• 4 Mark of Eviction
• 4 Sunken Field
• 4 Delusions of Mediocrity
• 2 Cephalid Shrine
• 2 Parallel Thoughts
• 4 Genju of the Falls
• 4 Genju of the Cedars
• 4 Still Life
• 4 Eladamri's Vineyard
• 4 Rites of Flourishing

• Lands (24)
• 12 Island
• 10 Forest
• 2 Simic Guildgate

Buy This Deck

I'd put in more Guildgates, but the Genju Auras need Islands and Forests to do their thing.

Delusions of Mediocrity won't leave the battlefield, so it's just blue life-gain. Similarly, Parallel Thoughts loses all its liabilities and is a tutor for all the things you want the rest of the game. Sunken Field is the best available Aura in the Shieldmage Advocate category, essentially reading, "Tap enchanted land: Counter target spell." Cephalid Shrine is a backup Sunken Field that leverages your generally empty graveyard (Shrieking Titan Head can make you discard, but that's it) and the Hydra's generally full graveyard; if a card with the same name as the spell on the stack is in the Hydra's graveyard, the Shrine will counter it. Also, this is probably the only time in the last five years a Magic article has referenced Cephalid Shrine for any reason. Ken Nagle, you're welcome.

And, if you get a first-turn Mark of Eviction on a Hydra Head, you probably will win. "Removal doesn't get cheaper than this."

Conclusion

The Hydra format is easily breakable if you're interested (WotC said as much), but more importantly, it's breakable with weird cards that aren't worth playing elsewhere. However you want to face the Hydra, whether playing existing decks or building new ones, keep the format's oddities in mind, and aim it all toward having fun. It excites me that there's a solitaire Magic format that Wizards has developed and tested to some degree; if I'm between games at my store's multiplayer night, I can pull the Hydra out and try to beat it.

What are some cards that you're excited about for the format? Put some hidden gems in the comments as well as your experience so far in facing the Hydra.