Sacrosanct
Legend
Honestly, I haven't played with the barbarian yet, so I can't say what it's like at the table. But it seems like a very strong ability, and may need a nerf. Although resistance is less potentially game-breaking, because unlike with free hp you are taking at least some manner of lasting damage every time you're hit.
Also, the point of the game is to have fun. I deeply resent the idea that it's somehow more "adult" to just accept a broken game and work around it in play. You can be perfectly "adult" and still not want to play a clearly broken game. My mature adult table's response to seeing the moon druid was:
1) Laugh for about five minutes straight. I'm not even exaggerating, we were trying to play but we just kept busting up laughing.
2) Vow that nome of us would ever play a moon druid again, because it is clearly way messed up.
You're right again. Because that's totally an adult response...
Look, the moon druid doesn't break the game. Not even close. I'm sorry you feel it's such a huge deal, but for most people it's not. And if any PC being more mechanically powerful than you at any point during the game upsets you, then yes, I'd posit that's a maturity issue, because it's the same type of reactions I see with kids. And if you're going to throw around hyperbole by calling the game a "clearly broken" one just because of the moon druid, then don't be surprised if I consider that less than adult behavior, because I think a comment like that is so over the top it's laughable.