What does Montana prohibit in med spa advertising?

Short answer
The cited rules do not settle this — they set limits, not a permitted list: false, misleading or deceptive advertising is unprofessional conduct, deceptive trade acts are unlawful, and limited-field licensees may not use "M.D." or imply they treat disease.

The advertising provisions that reach a Montana medical practice in the sections cited here are general ones: the uniform licensing statute and the consumer protection act. The uniform licensing statute makes a misleading, deceptive, false, or fraudulent advertisement or other representation in the conduct of the profession unprofessional conduct for every Title 37 licensee, and separately reaches a document or statement the licensee knows or ought to know is false or misleading. The medical practice act forbids a limited-field licensee who does not hold a medical degree from using M.D., D.O., or any word or abbreviation that would induce others to believe the person diagnoses or treats disease. Outside the licensing system, the Consumer Protection Act makes unfair or deceptive acts or practices in trade or commerce unlawful; the department may sue in the name of the state to enjoin such a practice, and a court may impose a civil fine of up to $10,000 per willful violation. None of these provisions mentions before-and-after photographs, testimonials, or discounts.