Required Wild Shape Mastery, Wild Shape High Mastery, Wild Shape Grand Mastery,  Must be a druid, and must be a subclass that is based on wildshape, like a circle of the moon druid.

Only selectable by druids, and they must be druids of the moon (or other wild shape based subclasses, or if DM allows it otherwise)

The druid has mastered their wild shape ability beyond that of normal druids and gain the following.

• The character's wildshape ability now lasts indefinitely, until the druid changes, or till their form reaches 0 HP.
• The character has double the normal allotted amount of times they can wildshape. 
• The CR rating in which the character can take shape of is now equal to their level in the druid class.
• The character can not only choose the shape they change into, but can determine  it's size up to twice that creatures normal size or as small as 1/10th the normal size of the creature, as well as determine what it's colorations are and other general looks as long as those changes do not add anything that would  blend creatures, so a bear form that normally does not have horns, could not be made to have horns. 
• The character can also make any part of their wild shape any size, so they could essentially have larger bits, or a larger tail, or larger paws etc. then normal, this is decided at the time of the shift. 
• The Character can add their proficiency bonus to all rolls made in their wild shape forms.
• While in Wild shape form They gain +4  bonus and advantage on the forms skills, such as survival or perception as an example.
• The Character always has a constant speak with animals going while in wild shape form.
• While in wild shape, they can cast spells, they require no components that are valued at 50g or less,  and require no verbal or somatic components either. If the character is level 20 or higher they can cast any of their spells in wild shape form and require no components for any required component with a price of 100g or lower. 
• The Character gains 1 to an ability of their choice.