Build a Hearthstone deck with only odd-cost cards and get a better hero power

Hearthstone lead designer Dean Ayala has discussed a new mechanic in Hearthstone’s next expansion, The Witchwood. It’s based on rewarding players for building decks with even or odd mana cost cards.

Here are all the Hearthstone: Witchwood cards  revealed so far.

Two new neutral legendary cards will deliver said rewards: Baku the Mooneater and Genn Greymane. Baku will upgrade your starting hero power if you build a deck with only odd-cost cards, while Genn will reduce your hero power’s cost to one mana if you fill your deck with even-cost cards.

Those cards are the linchpins of this mechanic, but there are a few other new cards that will benefit from it too:

from
https://www.pcgamesn.com/hearthstone/hearthstone-witchwood-even-odd-mana-cost