“Ok guys I have some ideas but I need you to trust me and stay out here.  Unless you want to seriously tangle with whatever just grinned at me”. 

Knowledge dungeoneering to see if I might know what that could be 7 

how large is the cage, shadow is trying to estimate the  weight of the cage.  

“I have some new skills that might make it able for us to get the rat and get out without fighting, or maybe incapacitate long enough to get it and close/relocj the door .  But you all can be prepared if it doesn’t work to intervene and engage.”

Well (with that roll) it could be a magic mouth spell like what you witnessed in the mask room.

The cage is maybe twice the size of a rat.

"Make your play and I'll come correct with plan B" Laladak unsheathes his greatsword. 

Tyris nods to Shadow to go ahead with his plan, holding his bow ready to attack if needed.

Oreus is frankly happy:

Fine, I'd say further exploration can wait, now we'd better bring the familiar back to shop owner, so he and his family are not blackmailed anymore: they can go away and speak freely about what they do know

He takes half a biscuit for him and gives the other half to the rat

(I don't know what you are waiting for Shadow make your move) 

Laladak sees Oreus trying to give the rat a biscuit and shouts, "Oreus watch out!" Laladak runs into the room and gets behind the chest with teeth and swings at it. 

"BEEFTOWN CHOP!" Attack: 17 Damage: 24

As Oreus reaches for the caged rat, the chest attacks him with a Pseudopod Attack: 21 Damage: 8 which hits Oreus. Oreus is grappled (escape DC 13). Ability checks made to escape this grapple have disadvantage.

Everyone roll initiatives, anyone with a initiative higher than 2 can act.

Fario's initiative 4

Fellian's initiative 4

Neither of the half elves can see that Oreus is in trouble and will act later in the round. 

Initiative 21

Tyris can take readied actions (Laladak took his while I was typing up the response).

(I really need to go to bed now)

Shadow will use his bonus action to disengage then moves into the room to flank the chest with Laladak And casts booming blade as he lunges forward in a piercing strike with his rapier.

Attack: 22 Damage: 14

take additional 4 thunder damage if target moves willingly before my next turn

Init 13

Oreus is totally surprised by the bite of the chest/mimic

What the...AHHH...let...duahh

With a great effort, red in face, he tries to get free (Athletics 19)

(if I am able to escape the grapple)

Oreus moves 10 feet back and breathes heavily

Initiative 17

Laladak holds his position and swings at the creature with another 

"BEEFTOWN CHOP" 19 Damage: 22

As soon as the thing int he room starts to move, Tyris looses his arrow, then immediately draws another and fires it right after the first.

Attack: 14 Damage: 11

Initiative: 14

Attack: 18 Damage: 5

Initiative: 18

Alben steps inside the room, and throws a firebolt at the chest: Attack: 13 Damage: 1

Laladak takes his readied action to bring his greatsword down on the mimic, which misses. (Not sure why you rolled with advantage, if you can't give me a reason I'm ruling that the 10 stands. I know you posted while I was typing/making the map so maybe you were trying to flank with Oreus, but that won't work.)

Tyris takes his readied action to shoot the mimic which hits (I'm going to say that all ammunition that hits the mimic is not recovered.)

Shadow attacks the mimic with his rapier which hits and the rapier is stuck to the mimic. You will need a Strength check DC 13 with disadvantage to free the rapier. 

Oreus escapes from the grapple and moves away from the mimic. 

Laladak kills the mimic, leaving his greatsword also trapped to the dead chest.

Shadow and Laladak both are able to free their weapons but you will probably want to spend some time cleaning them as they are sticky.

Everyone receives 35xp

Shadow will search the dead mimic

6

Shadow doesn't find anything interesting on the Mimic. 

XP Correction Everyone receives 64xp that's an additional 29xp for those who have already added it to your sheets.

ooc: Oreus is now level 3, when am I supposed to play him as such? after resting or right now?