Dynamic Wildshape [Preq: have the wild-shape ability] - while you are wild-shaped, you can, as an action (bonus action for Moon druid) change into another beast. Using this feat has two limitations.
The remaining duration of the wildshape is halved each time you change shapes.
The Maximum CR of the beast goes down 1 step (CR4 to 3, CR 1 to 1/2 etc) each time you change to a minimum/maximum of CR 0.
Monstrous Wildshape [Preq: have the wild-shape ability] - in addition to beasts, you can transform into monstrosities and dragons that you have seen and have some piece of (tooth, scale, feather, etc). You Do Not gain any spells or magical abilities, or items the creatures might normally possess.
Dynamic Wildshape - I don't think you need to downgrade CR as long as you just say that your hp does not refill as you shift.
Monstrous Wildshape - "You can be a monstrosity but not do any monstrosity things" isn't really worth a feat at all. In the movie, the owlbear form never does anything a regular bear couldn't do. I just saw it as reflavoring, which is free.
Dynamic Wildshape [Preq: have the wild-shape ability] - while you are wild-shaped, you can, as an action (bonus action for Moon druid) change into another beast. Using this feat has two limitations.
Monstrous Wildshape [Preq: have the wild-shape ability] - in addition to beasts, you can transform into monstrosities and dragons that you have seen and have some piece of (tooth, scale, feather, etc). You Do Not gain any spells or magical abilities, or items the creatures might normally possess.
Dynamic Wildshape - I don't think you need to downgrade CR as long as you just say that your hp does not refill as you shift.
Monstrous Wildshape - "You can be a monstrosity but not do any monstrosity things" isn't really worth a feat at all. In the movie, the owlbear form never does anything a regular bear couldn't do. I just saw it as reflavoring, which is free.
My homebrew subclasses (full list here)
(Artificer) Swordmage | Glasswright | (Barbarian) Path of the Savage Embrace
(Bard) College of Dance | (Fighter) Warlord | Cannoneer
(Monk) Way of the Elements | (Ranger) Blade Dancer
(Rogue) DaggerMaster | Inquisitor | (Sorcerer) Riftwalker | Spellfist
(Warlock) The Swarm