Just for fun, Psalm, casually begins walking up the side of the wall, onto the ceiling, and approaches Dain, hanging upside down as he replies,  "I mean... Don't get me wrong. I enjoy indiscriminately murdering big lunk-headed dungeon goons as much as the next guy. So, if that's the way we go, you'll have no objection from me." 

He points down the eastern hall. "But if we'd rather avoid any immediate confrontation, there's still plenty of roads not yet explored."

He continues walking down the opposite wall, returning to the floor to add with a glint in his eye, "Either way, I'm excited to see what new sort of trouble we can get ourselves into."

"Well," began Finn wryly in response to both Psalm and Dain, "whatever's behind Zyl's door sounds like trouble enough. I say we at least check it out... if it attacks, maybe we'll get lucky and can direct it towards the half-dragons." The half-amused, half-cynical expression on the pirate's face didn't exactly give a committed answer to whether or not he was simply joking.

"Alright, I think we're in agreement. But let us exercise a little caution."

Zylborin will stand 25' away from the door, and away from the half-dragons, and cast Mage Hand. A spectral dragon claw apparates from his cittern, hovers over to the door and tries to open it.

"Okie dokie." Says Psalm. He positions himself in a safe spot behind the central pillar and readying a shot with his short bow, ready to release at the first hostile target he sees...

Dain preps himself nearest the door, ready to go ham on whatever is on the other side.

Finn stood back about fifteen feet from the door, re-summoned his sword into his hand, and stood ready to act.

With the party at the ready, Zylborin's draconic mage hand makes its way to the door and begins to turn the handle. A few tugs with no progress and it becomes clear the door is locked.

[[ Positions of your characters look good? ]]

"Well that's anticlimatic," Dain says, saying the word incorrectly but confidently. "It's just a beast though, so how's about we bust this down?"

Dain will try to kick the door down. Athletics check if applicable: 21

[[ I may not have thought of breaking down the door that way (big brain fart on my part) but I'd say a 21 definitely works! ]]

Dain is able to shove and crash through the door, splintering it asunder as he bursts through. The room beyond is bereft of light, visible from what light seeps in through the now-open portal. In the center is a bulbous beast standing up. It doesn't appear to have eyes on its head but rather on a tentacle-stalk. Two other tentacles stand by above it with spine-lined edges. It stands on three stubby legs, giving the vague appearance of a milk stool.

Most of the room seems to be rather unkempt with the wastes of prior meals dropped on the floor like a carpet of crumbs. But there is a path of sorts towards two chests on the right-side wall.

The beast shies away from the light before the smells of the recent fight begin to waft in. (Smells. Flesh. Food?) Dain hears the telepathic message in his head as the creature takes in large breaths with its maw. It seems confused by the presence of a dwarf. (Food!)

Initiative Rolls

Dain: 21 
Psalm: 18
Sampson: 10
Zylborin: 6
Finn: 19

Milk Stool Beast (MSB): 7

Initiative

Dain, Psalm, Sampson, Finn <------- currently up
MSB
Zylborin (will be merged into the rest of the party after MSB goes)

Dain smashes the door down, satisfied by the ease at which it crumbles for him. He looks in on the creature within and winces, “Somebody beat you with the ugly stick for days, did’n they?”

The telepathic “Food” makes his mouth water for a second before he catches its meaning. “You want a taste o’ this axe then ugly? Dinner’s served.”

Finally stating down what he perceives as a worthy challenge, Dain will Rage, his cloth shirt ripping as he flexes through it, and rush the beast to deliver on his promise.

Attack One: 17 to hit for 16 Slashing Damage

Attack Two: 22 to hit for 15 Slashing Damage

Finn swore in confusion as he watched Dain rush in, then he levitated up several inches into the air and flew after him.

Entering the room, the warlock maneuvered onto the opposite side of the creature from Dain, then focused the cursing power of his patron towards the monster before spinning into action with his blade.

"YOU'RE the food, WE'RE the hunters!" he yelled defiantly as he slashed twice.

MOVE: Into the room, flanking the creature with Dain
BONUS: Use Hexblade's Curse to curse the creature; Finn will now crit on a 19 or 20 on his attacks
ACTION: Attack the creature twice
* Oversized Blade Slash #1 - Attack: 13, Damage: 14 Magical Slashing (add 2 extra on a crit)
* Oversized Blade Slash #2 - Attack: 15, Damage: 14 Magical Slashing (add 7 extra on a crit)

Still concentrating on Hex (just under 7 hours left?) End of turn!

Psalm will dart across to the open door, call out "Peekaboo" as he looses an arrow, then duck back behind the wall again and stow his shortbow.

TURN BREAKDOWN

Sampson rushes 30ft to the right, catching sight of the beast in the grey shades of his darkvision! He channels magical energy into his quarterstaff and summons a beam of light to strike the beast!

(Bonus action Shillelagh, action Sacred Flame)

(9 if the creature fails a DC 16 Dex save!)

MSB Dex Save: 9 vs DC 16

Dain rushes into, raging and landing solid blows on the beast. It can scarcely groan as Finn's oversized comes down on it. It blocks the first blow but takes damage from the second. 

[[ @Mao For Psalm, with him not having stealthed behind the pillar, would treat this as no an unseen attacker. But could definitely do a quick hide behind the wall for that with the  next round. ]]

The creature lets out a roar as Psalm's arrow passes by and Sampson's radiant flames engulf him. Looking bloodied and worse for wear, it strikes out at those around him. First whipping his tentacles around and then a bite.

Tentacle 1 @ Dain
Attack: 14 Damage: 7 bludgeoning and 2 piercing
On a hit, Dain is grappled and restrained.

Tentacle 2 @ Finn
Attack: 14 Damage: 7 bludgeoning and 1 piercing
On a hit, Finn is grappled and restrained.

Target: 1-Dain, 2-Finn
Bite @ Target 1
Attack: 26 Damage: 16
On a hit, make a CON Save

[[ Made a slight adjustment to Sampson's placement to keep him out of the half-dragon's 15ft breath cone. ]]

Initiative

Zylborin, Dain (raging, bardic inspiration from Zylborin), Psalm, Sampson (bardic inspiration from Zylborin), Finn <----------- currently up
MSB 61-damage (hexblade cursed)

[[ Don't want to mess up the die rolls, but the damage from the bite @Dain is of piercing type so your rage resistance will apply. ]]

CON SAVE: 20

Dain ducks under the swinging tentacle only to be caught in the leg by the beast’s jaws. “That’s not your meal you overgrown broughtworst!”

He swings his axe into the beast repeatedly. 

Attack 1: 25 to hit for 14 Slashing Damage

Attack 2: 24 to hit for 14 Slashing Damage

Quote from HFlex >>

CON SAVE: 13

 

[[ Oof. ]]

As the bite sinks in, Dain can feel the rot of the MSB's diet entering into his bloodstream, the beginning of a disease taking hold. He now feels poisoned as the effects begin.

Quote from HFlex >>

Attack 1: 17 to hit for 16 Slashing Damage

[[ Could you either roll a second die, representing the disadvantage? (Or could also declare reckless attack for the straight-roll.) the 12 on the other attack will be a miss. ]]

Given that the poison would change things, let's just say it was a Reckless Attack.