Been talking to a lot of the common folks in the community, and there seems to be an overwhelming consensus. No one seems to think Druid king is balanced. Some like it, some don't, but no one thinks it is balanced for the most part.
I was a bit surprised to see so few forum posts on the topic considering the fact I have yet to have a single conversation with a single player that thinks it is balanced and fine as is. So here is my outlining of what I believe is wrong with the deck, and proposed changes.
1) Chimera is simply too powerful. A lot of people complain about how a few crow cards can hand the game to 1 player. Chimera is worse. A few lucky draws early and a player can snowball the game in their favor AND rush a win AND block their opponent from advancing. This is too powerful an ability, especially since they stack with each other. It's a cool idea, but simply too powerful of a mechanic as is.
2) Agents that your opponent can activate when it is not your turn. This is an interesting mechanic, but again, quickly creates a scenario where the other player becomes helpless. If you get a few agents early, your opponent will have next to no counters. It's a fun idea, but needs balancing.
3) Vestiments and Wraith are simply too powerful, especially with the psijic deck. If a player gets vestiments early (god forbid turn one, it only costs 2 gold) then they can use any card with scrying on it to farm unlimited power. There's just no way this was intended game design, at least not in the manner in which some players are using the deck. It is possible by turn 4 or 5 for a player to be generating 10-20 power per turn before their opponent has had a chance to even buy a single decent card. That's not acceptable.
4) Bewilderment cards can HELP the opponent if they have forest wraith or other agents out. This is against the spirit of the patron. It's supposed to be a punishment you use on your opponent to counter their good luck, not a reward to them for their good luck. Especially if scyring is in play, it even then helps them there as its another card to cycle through. This is the only "detrimental" ability in the entire game. Honestly, I'd rather see other decks have "punishment" abilities before seeing this one neutered by an already imbalanced deck.
Here are my proposed changes as food for thought to show how you could maintain the spirit of the deck, but remove the unfair dominance and prioritization of RNG over all else:
Draoife Ritecaller/Eldertide Fenwitch - Change language to "When any card purchased from the tavern is placed in your cooldown pile, gain one coin." Removes the scrying issue, and also removes the ability to proc on your opponents turn/bewilderment
Druid King Vestiments - Change to "when any card purchased from the tavern is placed in your cooldown pile, gain one power." Maintains the spirit but removes the exploit of cycling cards with scrying. Also makes language clear that contract cards do not count for the bonus. I'd also consider increasing the purchase cost to 3 or 4 since this would still be a very powerful card for 2 gold.
Forest Wraith - Change language to "When any card purchased from the tavern is placed in your cooldown pile, gain one power." Same logic as Vestiments.
Stonelore Rockseer/Envoy of Draoife - "When one of your agents, excluding this one is activated or played, gain one coin." Makes no sense that it can activate itself since it already has the coin as a bonus. Also, again the ability for your opponent to increase your gold/power/prestige when it is not your turn, while novel, is simply too powerful in the current state of the game.
Chimera - Ideally, remove this card from the game all together as no other patron gets "multiple" bonuses when used. Changing the cards on the tavern is already a fine thing for the druid patron to do, and keeps it useful. However, if you MUST leave this card in the game... Remove taunt. Reduce health to 1. Reduce power gained to 1. Change 3 prestige to 2 gold. Simply put, this card is wildly imbalanced, and a player getting it early can end up with several of them which proc off each other and end the game early while the opponent has no opportunity to counter. That is WAY out of line with other patron abilities. The card is tremendously imbalanced vs. any other single card in the game AND how you obtain it makes the patron out of line with other patrons.
With these changes, druid would be "just another deck," not too strong, not too weak, and selecting it would be based on preference of play style. This would be similar in my opinion to changes made to Pelin, Rajhin, and Orgnum that took them from "luck is the most important part" to "use if your playstyle prefers," which greatly improved the game.