(PS: sorry, Randall only has to make 3 saves.)

OOC:  By initiative 1 the situation is nothing like it was at the beginning of the round.  Shall we resolve what happens to Petcan before Randall acts?

Yes, that's fair.

It is such a departure from the normal way.

I might just go back to the normal way. I don't want to use the "I roll initiative for everyone" method anymore.

@dm

the plants have to take 24 fire damage if they fail s Dex save, and then another 27 if they try to run through the wall. 
edit: half of 24 on a successful save. 27 is no save. They just take it. 

This may be wrong but I count the area of effect as the ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick.

2 scenarios can arise from this:

1. You cast it so they were in the area of affect, the actual fire, and therefore had to make a save or take 24, half if they make the save, and then they exit on the side that doesn't have heat where everyone else is.

or

2. You cast it to pin them in so they were within 10 feet of the wall. They moved through it on their turn and took the auto-damage, no save, and ended up on the side that doesn't have heat where everyone else is.

Is this wrong?

No it is correct; Nschrock its when they end their turn there or walk through the wall of fire:
"One side of the wall, selected by you when you cast this spell, deals 5d8 fire damage to each creature that ends its turn within 10 feet of that side or inside the wall".

I choose the option that did the most damage because I figured that is what you would of wanted, sorry for not asking first or clarifying.

I figured it’s hot in the wall’s whole area, which I thought included the ten foot area where it’s hot. I probably should’ve just cast fireball then, but lesson learned. 

Petcan raises a shield when the plants attack, deflecting all but 3 attacks 

4 con saves against blind

22 9 6 20 

And 3 concentration checks 24  16 23 

I’m blind and wall of fire is gone 

Randall (Initiative 1, Round 1):

Moving up to the edge of the plant’s mist but not entering it, Randall calls, “Come this way, Petcan, and I will heal you,” as the spirits encircle him.

(Still casting Spirit Guardians, but not entering the blinding mist—instead giving Petcan a frame of reference to withdraw to if he wishes).

Randall:

Initiative:  18

( Randall has Spirit Guardians in effect which will affect the plants if the approach him within 15 feet.  He is planning to heal Petcan if he can, but that may take different forms based on where Petcan and the plants fall in initiative.)

Spirit Guardians Damage for round 2 if needed::  10

Round 2 init; 7

Bow shoots 3 bolts at whatever plant is closest 

Attack: 11 Damage: 25

Attack: 8 Damage: 20

BA Attack: 12 Damage: 25

(ooc: to clarify a little, I will reconsider initiative options after this fight, for now include your initiative in your post for your round 2 turn... I have Randall and Bow's, others can post when the hangovers wears off, lol, Happy New Year everyone!)

Petcan initiative 11 

Petcan will follow the sound of Randall’s voice and cast warding wind on himself, hoping to hedge out any further issues with the plants’ mist

ooc: My init is in the spoiler

Tempe chases after one of the natives thinking his comrades have things well in hand if he can catch him or her. using a ki point to dash

Making his speed 90

subduing damage

Attack: 19 Damage: 15 

Attack: 19 Damage: 6 

(ooc: think I used Tempe's Intimidation roll of 17 for his 1st round initiative, so I'll use the 10 in the spoiler for his round 2 initiative... just another reason to go back to the normal way of rolling after this fight. lol)

Z casts Eldritch blast at whatever plants are still alive on his go.

Blast 1: 9 Damage: Unable to parse dice roll.

Blast 2: 11 Damage: Unable to parse dice roll.

Initiative 10

Using it on mobile so dice rolling seems a bit iffy. Damage is 1d10+3. Could you as DM please roll and resolve assuming 9 and 11 even hit?

Initiative:

PW1: 18 

PW2: 8 

PW3: 7 

PW3: 11 

PW1: 18 

2 more Purplewraths die.

Tempe flies after the natives closing 90 feet of the 120 distance. Since you stated subduing damage in your post which can only be melee I'm not counting your attack rolls for this round. (The clearing was 60 feet + fleeing natives can move 30 and dash for 30 which is how I came up with 120)

Zenodor's blasts pierce the purple mist and nothing else.

Petcan summons a gusty ball of wind extending 10 feet around him clearing all mist away in that area.

Randall can heal or do anything else he wishes on his turn as there's only 1 Purplewrath left (at the moment).

Bow fires 3 bolts, the 1st kills the remaining Purplewrath, the 2nd cuts it's dead stem of a body in half before it hits the ground, and the 3rd misses flying through where the body had been just moments before.

(This combat is over. You can chase down the natives and kill or capture as you see fit, whatever you decide will be handled outside of any sort of combat. Apologies all around for trying some new initiative option and switching midway through a fight, this just goes to show the tried and true method that has been used for decades through most iterations of the game is the best one. We will be using normal initiatives from now on as they allow for turn to turn reactions to what happens in a round and this seems to be best suited to how the game works mechanically.)

(Good news is... you all advance to level 8.)