I know it’s possible to gain immunity to e.g. conditions like poison, fear (both Heroes Feast), charmed, etc. It’s also possible to gain immunity to cold or fire damage, using their respective Investiture of Ice/Flame spells. Immunity to psychic can be gained with Mind Blank. There are also some magic items in the DMG that give immunities.
However, I have been unable to find anything that gives immunity to physical damage. Plenty of sources of resistance, but no immunity. The closest thing would be Otiluke’s Resilient Sphere, but that does not really give you immunity, it just interposes a non-circumventable barrier between you and your enemy.
Therefore my question: Is there any official source (both regular and unearthed arcana) that allows a PC to gain immunity to physical damage?
To clarify: with physical damage I mean bludgeoning, slashing and piercing damage.