Mordenkainen's Lost Notebook
4-level Transmutation
Red fur sprouts from your skin, and your spine twists. You hunch over until you stand on four clawed feet. A great heat fires your belly, and tendrils of black smoke curl from your fanged mouth, as you take the form of a hell hound (MM, p182). The transformation lasts for the duration, or until you drop to 0 hit points, fall unconscious, or die. You assume the hit points of your new form. When you revert to your normal form, you return to the number of hit points you had before you transformed. If you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form. As long as the excess damage doesn’t reduce your normal form to 0 hit points, you aren’t knocked unconscious. You are limited in the actions you can perform by the nature of your new form, and you can’t speak, cast spells, or take any other action that requires hands or speech. Your gear melds into the new form. You can’t activate, use, wield, or otherwise benefit from any of your equipment.