A lvl 20 Druid gains the Archdruid ability, which allows you to cast Wildshape an unlimited number of times. Does this allow you to recast Wildshape every turn?
Yes. If someone knocks you out of your form, just pop back in each turn. We think it's going to be rather hard to drop an archdruid. 
Gruff_Ironfist wrote:
I only have the PHB which doesn't list any CR6 beasts, what's a good example so I can judge how BA a lvl 18+ Moon Druid would be?
The DM Basic Rules has a CR6 beast in the Mammoth (and a few more non-beast CR6 creatures).
Archdruid still fairly easily killed by Power Word Death. Just pump some damage into him to get him below 100 hp and BLAM!
Yep, it looks pretty awesome on paper at least., but:
Eh, it's 20th level....
At 2nd level being able to turn into a CR 1 Brown Bear or Dire Wolf is frikkin' amazing. Esp. wou can just do this again when you're forced to revert back.
At 20th level turning into a CR 6 Mammoth or CR 5 Elemental looks far less impressive given what you're up against CR20+ creatures.
Sure you'll be able to cast spells in Beast form, which is pretty awesome. Elemental Artillary Mammoth!
... but you're not focused as a primary caster like a wizard, sorcerer or even Land Druid.
If either turns out to be horribly powerful in actual play, my easiest houserule to nerf both:
You cannot use Wildshape again for 1 minute (10 rounds) after you shift out of Beast form. (Whether voluntarily or forced)
I already made a thread about this in another forum, the Tarrasque has no hope of even scratching the archmoondruid real form if he turns into an earth elemental.
You ever notice how "an ancient evil awakens"? It's because no one can ever BEAT the ancient evil, they usually just lock it up or supress it somehow. So level 20 druid probably wont be able to just be killed out right.