Aruel's Improved Wild Shape

A spell created by a wizard that envy the druid's wild shape skill.

• when cast you assume the form of a beast or monstrosity that you had a part of. Your game Statistics are replaced by the Statistics of the beast, but you retain your Alignment, personality, and Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw Proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature's bonus instead of yours.
• When you transform, you assume the creature's Hit Points and Hit Dice. When you revert to your normal form, you return to the number of Hit Points you had before you transformed. However, if you revert as a result of Dropping to 0 Hit Points, any excess damage carries over to your normal form. For example, if you take 10 damage in animal form and have only 1 hit point left, you revert and take 9 damage. As long as the excess damage doesn't reduce your normal form to 0 Hit Points, you aren't knocked Unconscious.
• You can't cast Spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your wild form. 

the max Cr creature you can assume is equal to the spell slot level you use.