@AtomicDekeCan a willing shapechanger (i.e. a changeling) be affected by Polymorph, or does the auto-success saving throw come into play?
i'd let a shapechanger forgo the save – but remember that polymorph does change mental stats, so I'd rule NPCs opt to save
— Mike Mearls (@mikemearls) August 11, 2015
@JeremyECrawford Level 8 player casts polymorph on self to become T-Rex. “Retains personality and alignment” so still recognize allies despite Intelligence of 2?