Homebrew Druid

The rules for Beast forms have been altered slightly to make them more effective at higher levels. The forms you can take are no longer limited by CR and are instead based on the size of the beast.
Here is the new Beast Shape Chart:

Level	Size	Limit
2nd	small	no fly/swim
4th	medium	no fly
8th	large

Beast Shape Stat Modifications

As you gain more experience with the magic of nature, your beast shapes become more durable. Starting at level 3rd level the health pool for your wild shape forms are modified using the following formula:



HP   +      [(Druid Level) x 3] x (size)
where size is equal to:

tiny	+1/4
small	+1/2
medium	+1
large	+2

Tempting Fate Sizes

huge	+3
gargantuan	+4

You may add +2 to one stat of the form every time your character gains an "Ability Score Improvement" upon leveling in the Druid class. Just like with your normal humanoid form, this stat improvement is permanent for your beast form and cannot be changed

Circle of the Moon Changes

6th level feature replacement:

Flexible Wild Shape

When you wish to shift into your beast form you now have two different options to help diversify your combat options. You can either choose another beast form and swap between the two without expending a usage of wild shape, or you can swap between a beast form and your humanoid form without spending a usage. When you swap back to either form your health pool DOES NOT reset. You can only choose one of these options at a time.

Tempting Fate

In order to transform into a beast shape that is either huge or gargantuan, you must use life energy to maintain it.

Physical Strain

For the duration of your transformation, you will take damage equal to:
       (size)           x     (# HP dice)         d  (form HP dice)
(Druid Level)            (proficiency)

over the span of 
(proficiency)  -  1 rounds

Example:

A Tyrannosaurus Rex is a huge beast (size = 3) with a health pool of 13d12 + 52 (where 13 is the # HP dice and 12 is the form HP dice). At 5th level your proficiency is a +3.
Therefore, by plugging in the information to the above formula, the damage you would take is:
  3       x      13     d  12
  5                3                       


over a time frame of: 

3  - 1   =    2 rounds

Summary: As a T-Rex you take 3d12 damage every other round of combat at 5th level

Because you are Tempting Fate to perform something outside your normal skill set, you do not add the health modifier to the beast forms base HP.
In addition, you cannot boost any of the stats for the form for similar reasons.