Archdruid (VGtM)
Archdruids are to druids as Archmages are to wizards, naturally. Both sit at the top of their respective tradition, both have underlings, both can reshape reality around their pinky finger by using 9th level spells, both get really mad when you interrupt their breakfast with some trivial problem that could be solved by the town’s legal system or a party of t1-t2 adventurers. All I’m saying is that they don't put down their pipe unless it’s at least an Adult Dragon who is stealing all the pies in the kingdom, cause they have bigger problems to worry about.
In fact, the only likely way your party is ever going to meet one, is if the Arch-in-question is their patron. (Unless they are Elminster, or Mordenkainen. For some reason those two old dudes really like to make cameo appearances in adventures.)
In addition to being a really high level spellcaster you can buy spellcasting services from, Archdruids often serve as the head of a religion, sometimes even the head of state for a theocracy/magocracy, and most often they are the appointed guardian of an untamed wilderness area. Heck, they can even be all three at once. This level of status makes it trivial to find a place for one of them in your campaign, but a bit hard for the PCs to get a hold of.
So, I have to say it. Despite the changes in this book to make casters streamlined and easy to run, the Archdruid is still irrationally complex. This is due to the Change Shape power giving the Archdruid access to 200+ alternate stat blocks. Even more annoying, this complexity is practically useless in combat, because even a CR 6 dinosaur is nowhere near as deadly as a CR 12 caster. You could make an argument that an Earth Elemental is harder to kill in melee combat than an Archdruid, but that only deals the damage of a CR 5 creature, and you would be in melee range for no good reason. For lethalness, the Archdruid should just keep their distance (Tree Stride is amazing for this) and fling Wildfire attacks at the enemy. Wildfire deals significant damage up to three times per round, and blinds anyone hit by it with no saving throw for a turn, making it crazy good for control. In fact, it might be a good idea to snipe multiple targets instead of just one, because keeping two or even three PCs blinded is a huge boon in terms of action economy.
Mind you, the Archdruid can still cast spells when they are in animal form, but their entire spellcasting trait has been gutted. The highest level spell they can cast is 5th, instead of the 9th level spell they previously had access too.
Getting deeper into the changes: More hp of course, but less AC, and no access to the powerhouse that is Foresight, or the massive reset button that is Heal. This makes them way easier to kill. Better DPR in human form, but they can’t cast Fire Storm as a Giant Shark, which as we all know, is the pinnacle of nature’s wrath. At least Change Shape is a bonus action now, for what that’s worth.
Once again, I am disappointed. The issues could have been completely avoided by making Change Shape a more generic power that allowed the Archdruid to swap out their size, stats, movement speeds, and breathing organs for a handful of generic replacement blocks with their own attack and defense powers comparable to the humanoid form.