Hearthstone players will soon be headed off to The Witchwood, wherein they will discover 135 new cards, a new Dungeon Run-styled mode called Monster Hunt, and as lead designer Dean "Iksar" Ayala talks about in this new video, an interesting twist on deck building.

Even-and-Odd Decks are enabled by two new legendary cards that were revealed as part of The Witchwood expansion announcement. Baku the Mooneater upgrades the starting hero power for players who have a deck comprised exclusively of cards with an odd cost, (which means you'll get same hero power as Justicar Trueheart enables), while Genn Greymane reduces the cost of starting hero power to just 1 Mana for players who have a deck built of only even-cost cards.

In the video we also got to see four new class-specific cards that benefit from being either an even or odd deck: Black Cat for Mage, Gloom Stag for Druid, Murkspark Eel for Shaman, and Glitter Moth for Priest. They're each powerful in their own right, and should provide a strong incentive for players to experiment with the deck-building challenge of only using half your card collection.

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It'll be interesting to see what the Warrior, Warlock, and Hunter options are, as these classes feel like they could potentially benefit most from the even or odd-only effects. We already know how good the 'tank up' hero power is in Warrior, and being able to use Lifetap on turn one in Warlock could mean playing a Mountain Giant on turn three. Ouch.

Ayala dives deeper into the details of even and odd decks in the new video, and also talks a bit about strategies and ideas for deck building. More Hearthstone: The Witchwood card reveals will take place during a livestream set for March 26 at 11 am PT/2 pm ET on Twitch.

Update: On Reddit principal game designer Mike Donais has explained that not all classes will be getting their own even-or-mod matters card. Here's the explanation:

"There are only a few of these even/odd support cards like the ones shown. There is not one for each class. We aimed them at the combinations that we thought were going to see less experimentation/play so that people might try those out. For example even mage is an obvious choice, so we made a card for odd mage to increase its viability a bit. As with most build around cards these even odd decks are cool because as new expansions are released people will go back and look at the combinations again and pick some to experiment with."