ive been trapped in the jar for 10 days now, i keep showing up for dnd meetings but the dm has taken my place at the table and everytime i try to speak he tells me to 'shut up and get back in the jar'.

So basically a far cheaper version of lichdom

Far from it. You are not immortal and a simple spellcast of protection from good and evil will most likely just end up killing you.

True you are not immortal in the traditional sense but if you are smart about it you can attain a form of pseodo-immortality.

for example if a wizard somehow manages to get enough gold and resources to produce or procure enough young bodies through the clone spell or kidnapping they could theoretically posess new body after new body for basically forever.

The only downside is that you somehow need to keep your original body alive but this can be achieved through the Imprisonment spell as well as somehow managing to maintain a constant supply of fresh young bodies.

Quote from Mannimarco_lord_of_evil_kittens >>

True you are not immortal in the traditional sense but if you are smart about it you can attain a form of pseodo-immortality.

for example if a wizard somehow manages to get enough gold and resources to produce or procure enough young bodies through the clone spell or kidnapping they could theoretically posess new body after new body for basically forever.

The only downside is that you somehow need to keep your original body alive but this can be achieved through the Imprisonment spell as well as somehow managing to maintain a constant supply of fresh young bodies.

 Actually, it doesnt say the spell ends if your body dies. Food for thought.

Yes but it might be preferred to have your original body alive in case you want to return to it for some reason.

Get back into the Jar, jarboy

SO.... Can I:

A. Move my soul to a (let say) a mindflayer 100ft away...

B. The Mindflayers soul gets into the jar...

C. I slit my mindflayer throat as an action...

D. My companions smash the jar on their turn. I return to my body...

E. The mindflayers soul return to its bleeding out body and dies.

F. Profit ????

Mind Flayers aren't humanoids so wouldn't be viable targets for possession.

Assuming you do find a way to do it, if the host body (the mind flayer) dies with your soul inside it you have to beat your own spell DC with a charisma save or die. The DM might rule that the mind flayer's body doesn't make death saves since monsters rarely do. Pretty risky move. Probably better to let your party knock you out and come back with one hp. Then jump back and let the others finish the job.

Quote from Mannimarco_lord_of_evil_kittens >>

True you are not immortal in the traditional sense but if you are smart about it you can attain a form of pseodo-immortality.

for example if a wizard somehow manages to get enough gold and resources to produce or procure enough young bodies through the clone spell or kidnapping they could theoretically posess new body after new body for basically forever.

The only downside is that you somehow need to keep your original body alive but this can be achieved through the Imprisonment spell as well as somehow managing to maintain a constant supply of fresh young bodies.

 Hmm...  Using the Minimus Containment option of Imprisonment makes the prison gem unbreakable.  If you could finagle your DM into allowing the Jar for your soul be the same gem in which you Imprison your body, you would solve a couple of issues. 

As you say, the Imprisonment spell keeps your body from needing to eat, breath, or drink and stops aging.  It would also make the Magic Jar unbreakable, meaning that spell couldn't be ended by smashing the Jar until after the Imprisonment spell is dispelled, which takes a Dispel Magic cast from a 9th level slot.  This would mean you could easily and relatively safely, keep your Jar and body within 100' in case your host body is killed.  Might be an interesting trick for a recurring Big Bad Evil Guy.  The BBEG would definitely want to have proficiency with Charisma Saving Throws though for those times when the annoying player characters kill his host body.

For a wizard PC with a 9th level spell slot however, it would be far easier and cheaper just to use Wish to duplicate the Clone spell without the material component cost to achieve psuedo-immortality.

*Edit: removed accidental double quote

Quote from RonSnow >>

SO.... Can I:

A. Move my soul to a (let say) a mindflayer 100ft away...

B. The Mindflayers soul gets into the jar...

C. I slit my mindflayer throat as an action...

D. My companions smash the jar on their turn. I return to my body...

E. The mindflayers soul return to its bleeding out body and dies.

F. Profit ????

 Not exactly.  You can however, say...

A. Possess a guard of the evil king's castle

B. "Arrest" your fellow PC's to get them into the castle

C. Find a quiet place to have your party "deal with" your host body so you can upgrade to ...

D. Possess the king!  Appoint the rest of the party to high positions in your court.

E. You just won D&D.  ;-)

Can a Simulacrum cast Magic Jar?

While possessing a body, you can use your action to return from the host body to the container if it is within 100 feet of you, returning the host creature's soul to its body. If the host body dies while you're in it, the creature dies, and you must make a Charisma saving throw against your own spellcasting DC.

It says 'if the host body dies', does this mean you can return from the host body to the container if the host body is only rendered unconscious?  Or can you not leave the host body in this state because it requires an 'action' that you cannot take because you're unconscious?

Quote from AncientGammoner >>

While possessing a body, you can use your action to return from the host body to the container if it is within 100 feet of you, returning the host creature's soul to its body. If the host body dies while you're in it, the creature dies, and you must make a Charisma saving throw against your own spellcasting DC.

 

It says 'if the host body dies', does this mean you can return from the host body to the container if the host body is only rendered unconscious?  Or can you not leave the host body in this state because it requires an 'action' that you cannot take because you're unconscious?

 .

Technically (RAW), you wouldn’t be able to return because you’re unconscious.  But, you could always tie up the body before leaving it, if you want to leave the host creature helpless.

If we were to be a little creative with the rules, you might be able to Ready the “leave” action to trigger when you take damage, if you are really dead set on getting a knock-out.

Yes that does work youd need to combo polymorph the intended target creature into a humanoid first 

he turned himself into pickle he is picklewizard. funniest thing I've ever seen

Step 1: Become a lich.

Step 2: Cast magic jar on a strong body.

Step 3: Use imprisonment to minimus contain your old body and wear the gem as a necklace.

Step 4: Set the spell to release a few minutes after your current body is killed. 

Step 5: Strap the magic jar to the back of some nasty beast or something and use burial on it. 

Step 6: If anything manages to kill you your soul will transfer back to your original body in your necklace and whatever managed to kill you now also has to deal with a lich

Step 5 wouldn't work because you need the magic jar to be close to you when your current body dies. 

Ah, you are correct. You could keep the jar on your original body then.

In a campaign I am playing, one of my fellow PC’s is playing a Wild Magic sorcerer, and cast this spell, then possessed his own body, then got a 91-92 twice on the surge table within 1min. The DM made the double roll permanent, so he now has about 3 lives.