Arissa viciously mocks the tree.

"Ha, it's just a bit of old wood! Looks like its bark is worse than its bite!"

Damage: 4

Frandal quickly releases two arrows. The first one, streaked with flames as it flies toward the tree misses its intended target. The second arrow makes contact but bounces off the tree bark harmlessly. 

Round 2

Continuing his struggle against the strength of the roots that have seized him, Thoradin breaks free as he simultaneously spits out a dwarven curse on the tree. 

The tree, seemingly looming larger and more sinister, lashes out again with two roots in attempt to grapple its prey. The first root, once again, makes an attempt to encircle Thoradin, the second root shoots toward Slasher.

• Grapple attack on Thoradin: 14
• Grapple attack on Slasher: 18

The roots prove to be too quick to avoid; both the dwarf and the Kenku are ensnared by tree. Continuing its attack on the party, the tree lumbers forward to bring itself within range of more targets, and then swings two of its branches, one at Ysander and the other at Arissa: 

• Branch attack on Ysander: 29 | Bludgeoning damage, if successful: 24
• Branch attack on Arissa: 28 | Bludgeoning damage, if successful: 19

Ysander reels from the heavy thump of the branch, spitting blood he stands straighter and prepares to cast once more. Calling the shadow blade back to his hand he prepares to defend himself but also casts another spell trying to remove the creature from the Shadowfell entirely. "Begone!"

Con save for Shadow Blade 24

Casts Banishment Charisma Save DC16

With a curse, Frandal tries to repeat its attacks against the branch that holds Thoradin again,

Firebolt: Attack: 9 Damage: 10

Attack: 26 Damage: 35

To Ysander's dismay, the tree remains where it is, and Thoradin and Slasher, therefore, continue their struggle with the roots that have surrounded them. 

Frandal's fiery arrow sails wide of its target once again, but his second arrow pierces deeply into the root that surrounds the dwarf. The root, however, maintains its grasp on Thoradin who yells, "You'll have to slash the roots! Arrows'll do no good!" 

Thoradin fails to repeat his escape from the tree's root. Pinned to the ground, he is helpless to do anything this round. 

(Round 2 actions for Arissa, Ozum, and Slasher are next)

Ozum once again shouts out a druidic call as another streak of lightning connects with the tree.

Call Lightning (4th level): DC 16 Dex save; fail 23 lightning damage, save half damage

Ozum calls forth another bolt of lightning; it strikes the tree with its full force and, subsequently, creates a deep split in the trunk of the tree. 

Slasher not believing he has the strength to break free from the trees grasp he casts misty step to teleport 30 feet away from the tree. Slasher quickly turns back and charges back at the tree, he will not run from a fight. First Attack: 17 Damage: 10 Second Attack: 16 Damage: 8

no off hand used a bonus action for misty step

Nevermind just read the messages sorry. Forget the misty step.

Slasher seeing his new found companion get grappled by this tree once again swings his blades at the roots *mimics sound of a barbarian battle cry*

Offhand Attack: 21 Damage: 6

For a second time, the ranger charges at the tree and cuts three deep wounds into the monster's trunk. 

(Arissa's action is next).

Arissa casts vicious mockery. (WIS 16)

Damage: 4

 While maintaining its grip on Thoradin, the tree seeks to grapple the Kenku who has repeatedly cut into its woody flesh. (Grappling attempt: 12)

Slasher proves yet again to be too elusive, and the ranger easily avoids the root. The tree persists in its effort, however, to fight off the Kenku by swinging two of its branches.

• Branch attack 1: 17 | Bludgeoning damage, if successful: 16
• Branch attack 2: 21 | Bludgeoning damage, if successful: 18

 (Player's may take their actions in any order)

Slasher is briefly disoriented by the massive blows from the tree but quickly shakes it off this tree needs to be cut down blood dripping from his beak Slasher swings his swords once more trying his best to hit the root/branch that holds Thoradin. First Attack: 24 Damage: 12 Second Attack: 14 Damage: 7 Offhand Attack: 24 Damage: 6

In a blur, the ranger's blades fall upon the root that has ensnared Thoradin. A moment later, the dwarf is free and the tree root is, lifeless and cut in multiple pieces, lying on the ground. 

"Well that was some impressive swordplay, we won't be short of firewood tonight.  Master dwarf are you alright?  You seem to have taken quite a beating, it pains me that my attempts to save you were so ineffective, I pray that next time I will give a better account of myself."  The sorcerer says this while turning a slow circle still holding his shadow blade defensively as he peers at all the other trees looking for signs of activity. 

Perception 21

(The root that grappled Thoradin has been destroyed; the tree itself, however, lives)

"I thought that had killed it, this thing doesn't want to give up - hopefully this will work better." Again  the sorcerer tries to damage the tree t hi s time hurling a filming bolt at it.

Casts Fire Bolt

Attack 14 for 10 Fire damage 

A small sphere of fire shoots from Ysander's hand, but it whizzes past the tree, causing no harm. Thoradin, enraged by the tree's persistence, rears back with his warhammer and attempts to deliver a smashing blow to the tree's trunk (Attack: 21 | Bludgeoning damage, if successful: 7)

(Frandal's and Arissa's actions are next)

“I am trying to burn it “ replies the elf making his arrow ignite again “but this atmosphere seems to impede my magic... “ 

He concentrates and attack the tree again

( Firebot and arrow once more:

Attack: 17 Damage: 14

Attack: 18 Damage: [roll](if([roll:-1:critical], =0, 1d8+1d6, 2{1d8+1d6}.expand()))+17[/roll )

Edit after seeing the rolls.

Still his words came true again as both attacks go wide off it’s target.

*What’s wrong with me? I can hit a copper coin from 200 feet without aiming and I can score a direct hit on a huge tree just in front of me...*

( I unintentionally deleted the las /roll from the formula when I started editing so I expect the red banner. In case it mess with the rolls, it was a 4 and a 9 to hit... ) 

Ozum sends another lightning bolt down on the tree.

Call Lightning (4th level): DC 16 Dex save; fail 22 lightning damage, save half damage