As Beegred's arrows splash into the Pudding King, Glabagool responds to Beegred, "I don't understand what you say... The Pudding King doesn't convince us to battle... He promises us a feast at the wedding.  And if you want the Pudding King to go down, I can carry him down a hole somewhere.  Just have to find one."

The Pudding King retaliates, "What madness?  They are not your friends, consume them!" 

When Glabagool doesn't immediately act at those orders, The Pudding King continues, "Then feed ME!"  The Pudding King thins himself out as he plasters his diminished oozing form against the large cubic form of Glabagool.  The almost translucent color of Glabagool is easily distinguished from the mucus color of The Pudding King.  However, you are all no longer certain you can harm The Pudding King without also harming Glabagool.

(Orubis and Skameros's turns)

Orubis readies and throws more magic stones

Attack: 9 Damage: 6 

Skameros is, to say the least confused and stunned at the turn of events.

"No eat Glabbagool! Bad Pudding King!" and he throws a couple rocks at them.

[Stone: 2 Damage: 4]

[Stone: 14 Damage: 1]

then shouts "Sorry Glabbagool!"

Orubis and Skameros both throw a handful of stones, clearly hitting The Pudding King, but the stones also end up in Glabbagool before the magic in the stones fade.

Narstin limps along with Rodolfo's aid.

The last remaining Strike Team member standing does their best to grab a hold of another unconscious Strike Team member and starts to drag them away, out of the cavern, yelling angrily at Burrow Warden Jaeger, "Can't kill that Pudding King, and I can't save everyone either.  We're useless."

(Thurnir's turn.  Then Rodolfo)

(Going a bit theater of the mind here... Rodolfo no longer has line of sight to The Pudding King or Glabbagool as he moved south with Narstin)

Rodolfo will continue to help Narstin and keep moving out (he's also out of all spell slots).

Thurnir just keeps shooting, trying to aim to hit the pudding king mostly if he can..

16 to hit

8 magic piercing damage.

(The Pudding King is nothing more than a paper thin sheet trying to wrap itself around a much larger gelatinous cube).

Thurnir shoots The Pudding King and his magical bolt causes the snot colored ooze of the Pudding King as well as the clear transparent substance of Glabbagool to sizzle and burn.

(Now at the top of the round)

Glabbagool responds with an alarmed and surprised telepathic blast, "What!?  I will not be your feast.  You promised a feast, not be become a feast!"  In retaliation, Glabbagool attempts to engulf The Pudding King...

Pudding King DC 13 DEX Saving Throw: 2

At first it appears that The Pudding King ooze replenishes itself as it tries to wrap itself around Glabbagool.  Then in a sudden fight of wills, Glabbagool engulfs The Pudding King, causing the snotty ooze to fold in on itself and get compressed into a rather small ball which now floats inside Glabbagool.

The Pudding King telepathically projects surprise at first, but then cackles, "Ha ha!  Yes, protect me, my faithful servant."

Glabbagool telepathically projects out to everyone, like a sick child about to vomit, "Ugh, I don't feel so good..."

(Beegred's turn)

Beegred: "If it doesn't taste good, then spit it out."

Unwilling (at the moment) to harm the gooey ally, the halfling will Ready an attack action with the bow.
He still has the Hunter's Mark to help track the location of the evil ball of goo.
If it comes to the surface or is otherwise exposed, it gets 2 arrows (rolls inside the spoiler).

The Pudding King, comfortably cocooned inside Glabbagool, reaches out to his minions, "To me!  Offer me your bodies for protection, as this faithful subject has done.  And snack on these offerings I give you.  Just a small taste compared to the feast we will be given by the Faceless Lord at the wedding!"  The answering telepathic screams are so loud now, their arrival is imminent.

Burrow Warden Jaeger/Elemental hesitate for a moment, unsure about this new development.  The head of the ghost pops out of the elemental for a moment to speak, "Gather the unconscious and RUN."  Then the ghost re-enters and the arms of the elemental reach into Glabbagool to attempt to shove The Pudding King out where it can be attacked.

Elemental DC 12 STR check vs. Glabbagool: 12

The elemental's appendages are not made for the task, but it barely manages to coax The Pudding King out of Glabbagool, where it flops on the ground.  The elemental's arms are greatly reduced, having been dissolved by the acid.

Glabbagool immediately responds, "Ugh, that was vile.  What is wrong with you, my King?"

Beegred sees his opportunity and immediately peppers The Pudding King with two more arrows.  Two significant portions slough off into pools, which bubble and mix with the dissolving cavern floor.  There is not much left of The Pudding King, its form greatly reduced.  (At this point, he's barely large enough to be considered a medium creature)

With panic in his thoughts, the Pudding King once again telepathically projects, "Hurry to me!  Protect your King!".

(Orubis and Skameros's turns)

Orubis conjures more stones, but then raises his box on the necklace and casts guiding bolt at the Pudding King

Attack: 24 Damage: 13 

Three new stones appear in Orubis's hand, held out for Skameros.  With the other hand, Orubis fires a flash of light, hits the diminished form of The Pudding King, which then glows dimly.  (Advantage on next attack)

(Skameros's turn)

Skameros chucks two more magic stones at the Pudding King

[Magic stone: 6 Damage: 4]

[Magic stone: 17 Damage: 8]

(Advantage roll, for the first attack:  16)

Skameros scoops two stones from Orubis's hand and winds his arm a couple times before throwing the stone, which hits The Pudding King's oozing form with enough force to send a large chunk of his remaining form splattering. 

The Pudding King begins ranting, "“You haven’t won! No! We will rise from our children! We will be reborn from the Faceless Lord! Juiblex will consume the banquet of the Queen of Fungi and we … will … all … grow … !”

The rant is cut short when the second stone hits.  And like the flame of a candle being snuffed, all the mental cacophony of thousands of oozes randomly shrieking "FLESH FOR THE FACELSS GOD" suddenly stops.  The quiet is deafening until once again, cheering can be heard from a distance.

As all of you stand there looking at the puddle that is the remains of The Pudding King sizzling away at the cavern floor, Glabbagool silently surges forward and engulfs the earth elemental...

Orubis looks for anyone dying, readying to heal and stabilize by the grace of the Mushroom Prince, all the while saying a prayer in thanks

Thurnir looks around at the army of oozes-  are they still attacking?   

Beegred double checks his Hunter's Mark to be certain that PK is dead, instead of PK doing some fancy magic pretend-dead thing.

Beegred's Hunter's Mark no longer provides any connection to The Pudding King.