my dm didn't want us to engage so we engaged but from a cliff  but then dm made  the worm run so we stoped

Quote from TheSumoFrog >>

Two poison questions to ask:

1. The poisoned condition is not the same as taking poison damage, correct?
2. A critical hit (natural 20) by the Purple Worm does not double the poison damage, correct?

If you have any rules references for your answer, please do point me to them.

Thank you!

1.  They are different.  Most things that give poison damage also give the condition, but not all (such as this worm).
2.  A crit does not double the poison damage, as it's behind a saving throw.

Make sure you walk without rhythm if you're trying to avoid these things

Dune, anyone?

Walk without rythm...

purple funny 

The spice must flow

Wow....this is one nasty critter. Its stinger deals insane amount of damage from its poison, and it has a near impossible saving throw against that poison. Its bite can do a great amount of damage, at the same time swallow you whole, and it can couple each of these attacks every round with each other... This is a perfect way to chew through your characters very quickly. 

I love this monster!

 Be a Wizard, get proficiency with Poisoner's Kit, cast Simulacrum on yourself (or cast it through Wish to avoid the huge cost of the components), have your simulacrum cast Magic Jar and posses the worm, destroy the jar, (relatively due to the ability check on harvesting) safely harvest as much poison as you want, making your Rogue love you, getting a CR 15 pet/mount and becoming a super-rich criminal overlord, all in a good day's work.

Unfortunately this particular method would not work for two reasons:

1) your simulacrum is made from a spell, and therefore has no soul. As the magic jar spell description makes clear, the caster needs a soul for the spell to work

2) the magic jar spell only works on humanoids, "You can attempt to possess any humanoid within 100 feet of you that you can see" 

However any arcane caster (not just a wizard) could attempt to use the wish spell that you used to circumvent the hefty cost of the simulacrum spell to just take control of the creature directly, this is of course up to your DM's discretion however.

Quote from Vaprak_The_Destroyer >>

It doesn't really b=make sense that it has a walking speed.

 It wriggles and squirms just like a normal earthworm.  

Quote from TheSumoFrog >>

Optional rules for the Purple Worm, to enhance the story, the excitement, and the danger of a purple worm encounter. It also leads to a fascinating opportunity for a worm to engage in hide and seek (i.e., burrow away, and return for another Erupt action).

The purple worm should have a Lair Action to Erupt from either the ground (below), the ceiling (above) or the wall (side) on Initiative Count 20. This Erupt action is how it targets the largest, heaviest mass of creatures (on the ground; not in the air or incorporeal) in the party. It is like a Mammoth's trample action, in some respects. This article in Dungeon Solvers does a great job of explaining the difference between a Lair Action and a Legendary Action. Since this action occurs on Initiative Count 20, in a certain location (i.e., a "lair") and is not from a pool of limited resources, it is best described as a Lair Action.

Note that the Lair Action (Erupt) occurs on Initiative Count 20, but then the Purple Worm also gets it's normal multiattack (one with its bite and one with its stinger) during its initiative role. Since the Dexterity modifier for the Purple Worm is -2, the highest its initiative would be is 18. It can only perform the Lair Action after it has completely burrowed away and then returned. So at best it could Erupt on Round 1, burrow away on Round 2, Erupt on Round 3, burrow away on Round 4, and so forth.

Erupt Lair Action (Bite)

The purple worm will focus on a 10' square (4x5' squares, 10'x10') within it's normally occupied space, for the space it moves into. For example, it will Erupt under 6 creatures, but one 10' square has 3 creatures in it, so that is the square the purple worm will "attack" with it's Erupt lair action. All creatures in the 10' square are attacked by the BITE only (+14 to hit, 3d8+9 piercing damage), which has Advantage, if coming from above or below. All creatures hit by this BITE must save (DC19 DEX) or be swallowed. Any creature NOT swallowed suffers the same fate as all of the other creatures from the Erupt action; i.e., they now have to go through the Erupt Lair Action (Tossed).

Some thoughts on dimensions

• Purple Worm space (i.e., what it physically occupies) is either 3x3 (15' diameter) or 4x4 (20' diameter).
• Purple Worm attack (i.e., what it can bite/potentially swallow) is 2x2 (10' diameter). This corresponds to it's ability to swallow whole a Large creature (2x2, or 10' diameter).

Some thoughts on direction of attack

A purple worm is not smart, it is instinctive. So it will attack from a direction based on straightest path to largest food (i.e., guided by tremorsense). So it might be from the ceiling (above), from the floor (below), or from the side. DM has the final say; but I would provide advantage for an attack from above or from below; but not from the side. So the worm does not know how to maximize for advantage, but the DM should know that depending on the attack angle, it might exist.

Erupt Lair Action (Tossed)

Each creature in the Purple Worm's normal space (3x3 or 4x4 depending on size) is tossed aside (in the air, rolling tumble) and showered with debris. This becomes a Skill Challenge for each party member.

1. DISTANCE - Roll d4 (or d6) to determine how far the creature was tossed (Result x 5', or up to 20' or 30').
2. DAMAGE - 4d6 damage if the creature fails a DC20 (Hard) Dexterity saving throw, half if save.
3. PRONE - DC15 (Medium) or DC20 (Hard) Acrobatics (Dex) skill check to determine if the creature landed on its feet or is prone.
4. RESTRAINED - DC15 (Medium) or DC20 (Hard) Athletics (Str) skill check to determine if the creature is free of rubble or restrained by it.

Erupt Lair Action (Debris)

Each creature not in the Purple Worm's newly occupied space, but within either 15' or 20' of it, is showered with debris.

1. DAMAGE - 2d6 damage if the creature fails a DC15 (Medium) Dexterity saving throw, half if save.
2. RESTRAINED - DC15 (Medium) Athletics (Str) skill check to determine if the creature is free of rubble or restrained by it.

 

 Keeps things simple yet super effective with the classic vomit!  Mechanically, a purple worm vomit ability should be similar to an adult black dragon.  That way, even flying creatures aren't completely safe from the worm.    

Purple worm: *appears*

Most players: Ohhh nooo not a purple worm!!

Poisoners: *pushes up anime glasses*

Nasty!

My player used to be a lawful good clerik warforged. He  was super delighted charecter that never did damage and allways heal. But now he  splitted the party a Dungeon masters greatest weakness  soooooooooooooooooooooooooooooooooooooooooooooooooo PURPLE WORM!!!!!!!!!!!!!!!

Profinciency bonus

Aw, yes. I recently was allowed to have one of these as a pet for a Strixhaven game we are starting. I'm playing a wood elf alchemist spore druid enrolled in witherbloom. I was allowed poison immunity sense I was originally trying to play a yuan-ti pureblood, but he said instead of magic resistance I could add the wood elf template on top of it. I named my purple work Richard. He lives in the detention bog. I am going to open up a potions, poisons, and perfume  shop. The only rule is I can't use Richard for any important story based battles. I just love the idea of my character saying (in a British accent) "Would you all like to meet my friend Richard" and just a giant purple worm coming out the ground.

The walking speed would be for when it isn't actively burrowing. So while in combat in the open or moving through open terrain, such as the surface in the desert.