With the latest nerf patch making the game a little bit slower again, I ventured to the ladder with Quest Druid! Rogues have come out of their hiding places, and Druid is traditionally fairly good against Rogue, so I figured this old archetype might be playable again.
I went 9-6 with this deck in Legend for a 60% winrate, and felt like I could have done better as in the first games I was still looking for the right approaches to matchups. Demon Hunter is unfavored with Quest Druid still despite the nerfs, but I did well against everything else I found on the ladder, including many Rogues.
Just try to survive and complete your Quest and from there you have tons of value packed into every turn. Against Rogue, you need to get your Ysera to get some free dragon boards to overwhelm them because they have almost infinite value. Against most other opponents, your healing and regular minions will get the job done.
Quest Druid decklist

Deck code: AAECAZICBCT4oQP2rQPxugMNQFZf/gH3A8QGuZQDqaIDyKID76ID2akD+bUDxrcDAA==
I used this list, which is two cards away from the list that I originally theorycraft for the expansion. The major change here is the addition of two copies of Crystal Power to better contest Demon Hunters.
After you complete the Quest, Crystal Power first deals two damage to a minion and then heals it for five. If the minion has one or two Health remaining, it dies before it would get healed. You can also still heal your face with Crystal Power after completing the Quest: it does not deal damage to Heroes but allows you to target Heroes for the healing effect.
There is a lot of healing in the deck with Crystal Power, Steel Beetle, and Hidden Oasis, so you can come back from difficult positions and stabilize once you have enough mana and the Quest completed.
Ysera and Cenarius are the main win conditions. Archspore Msshi’fn is also playable in this deck as an early Taunt minion and later in the game as a 9/9 Taunt + 9/9 Taunt with Rush. Not that 18/18 stats for 10 mana is that special anymore, but it’s OK.
Quest Druid mulligan

You always keep the Quest and Crystal Merchant.
Against aggressive decks, you want Crystal Power (against Demon Hunter) and Wrath (against everything aggressive).
Against slow decks, you want Nourish. Nourish can also be kept against midrange decks if you have some early game already. Against Demon Hunter, it is too slow.
Quest Druid gameplay video
Finally, here is a gameplay video of me piloting the deck in Legend. It showcases how resilient the deck can be in the face of many, many threats – and how sometimes the opponents can still be too fast for you.