What Sanford doesn't know is where you are now in relation to the world above. He has only explored Kholias above ground. 

Is there anything else people want to do before pressing on to the Elven camp?

(I no one else has any questions, let's continue on.)

You pack up your stuff and move out toward the Elven Camp, Amiz keeping a close eye on Sanford as you travel. Much more of the same in the Underdark as you go, the river slowly gurgling next to you as you walk, the smell of limestone and moss, and the bioluminescence lighting your way. 

Random Encounter Roll (with an encounter on a 14+): 19

You eventually step out into a gigantic cavern full of stalagmites and stalactites all around. On the wall to your right you see a sigil carved into one of the stalagmites.

"A sigil of woe? Or merely a mark?" ponders Draíocht. "If a threat, I do have dispel magic on hand. But not sure if that may be needed."

[[ He'll offer guidance if there's any arcana checks to be made. ]]

Valar will attempt to determine the sigil: Arcana: 3; history: 14

Valar cannot discern the meaning of the rune just by looking at it. Although it looks somewhat elven.

If it's Elven, Draíocht tries to see if there's any writing he can recognize from it.

Draíocht History Check: 12

Draíocht can't understand the text either. It must be the language of the High (Fallen) Elves, which is very different to his people. 

14

At that moment, a Large flying bat-like creature drops down from the sky above, Amiz and Valar are Surprised by the Cloaker as it tries to attack the party, yet Amiz is able to pull out his axe in time. Initiative:

Group 1: Amiz and Thelanis

Group 2: Cloaker

Group 3: Draíocht and Valar

Amiz and Thelanis are up. A Cloaker descends, looking for easy prey.

I will out until sunday

Thelanis blasts the Cloaker as it descends.

Eldritch Blast: AC 14, 10 damage. AC 20, 5 damage. (Game log)

Amiz throws a couple Handaxe's at the Cloaker:

Handaxe 1 Attack: 20 Damage: 8 Slashing

Handaxe 2 Attack: 15 Damage: 6 Slashing

The Cloaker then drops on Valar, first trying to Attach to him with it's claws:

Attach against Valar Attack: 18 Damage: 13 Piercing, and the Cloaker attaches to him on a hit.While the Cloaker is attached, the target has the Blinded condition, and the Cloaker can’t make Attach attacks against other targets. In addition, the Cloaker halves the damage it takes, and the target takes the same amount of damage.

The Cloaker wraps its wings around Valar, then makes two strikes with it's Tail at the Paladin with Advantage due to him being Blinded:

Tail 1 against Valar Attack: 22 Damage: 5 Slashing

Tail 2 against Valar Attack: 24 Damage: 13 Slashing

You all are up. Valar is Blinded by the Cloaker who has attached itself to him. If you hit it, you also hit him.

Thelanis tries slashing at the cloaker, not realizing Valar is getting hit until he grunts in pain.

Longsword: AC 27, 11 slashing 1 necrotic

Draíocht wildshapes into a brown bear after Thelanis strikes and then tries to use that strength to dislodge the cloaked.

Athletics: 9 +4 (can't remember STR stats off the top of my head with quick post)

Valar takes 5 Slashing and 1 Necrotic damage from Thelanis hitting him through the Cloaker

Contested DC 13 Athletics check from Cloaker: 9

Draíocht is able to rip the Cloaker off Valar. And the predator turns on him in his Bear form.

Valar and Amiz are still up. Valar is no longer Blinded and can see the Cloaker turning on Draíocht.

Amiz and Valar try to attack the Cloaker, but are unable to get a strike on the Cloaker very effectively. The Cloaker attempts to Attach to Draíocht:

Attack: 23 Damage: 17 Piercing, and the Cloaker attaches to him on a hit. While the Cloaker is attached, the target has the Blinded condition, and the Cloaker can’t make Attach attacks against other targets. In addition, the Cloaker halves the damage it takes, and the target takes the same amount of damage.

Draíocht dodges out of way of the Cloaker, but the beast is able to throw a couple tail slashes at Draíocht:

Tail 1 against Draíocht Attack: 13 Damage: 13 Slashing

Tail 2 against Draíocht Attack: 22 Damage: 13 Slashing

You all are up. The Cloaker is attacking Draíocht now.