As the party backs away so that they aren't spotted and the sounds echo through the tunnels, the leader barks an order in Goblin.

The three goblins by the fire run into the tunnel. The three by Sildar wait and listen.

"Okay then. Let's take out the three that went to search. Quickly!" Feu says to the others.

Paren says "Now create an illusion of a big pit and rest of us can go attack and get Sildar"

Paren "Ready?"

Rweni stands confused, “Attack the goblins guarding Sildar or attack the goblins that just ran out?”

Feu, immediately realizing Paren's idea, cast Minor Illusion again and makes a 5 feet wide pit on the path the Goblins crossed. "The ones with Sildar." Feu starts to prepare as their pendant starts to shine brightly. "Didn't think of that. Good idea, Paren."

"Now." Energy starts surging through Feu. "Let's get them."

(We technically get advantage on our first attack, correct?)

(Also, is Sildar currently in the way of the leader? Would there be any danger of hitting him from range by targeting the leader?)

(Sildar is chained to stay held up between those two stalagmites. He is in the way of the leader and would cause the leader's AC to be +2 higher.)

(You won't have advantage on attacks unless you have cover to remain unseen.)

(You have surprise, though, so you all get to go before the goblins.)

When everyone is ready, Paren will move stealthy up to the leader and attack. 

Hand: Attack: 19 Damage: 4

Foot: Attack: 21 Damage: 6

If I get advantage then consider these as well.

Hand: Attack: 9 Damage: 7

Foot: Attack: 25 Damage: 8

Rweni places one of her magic stones into her sling and twirls it around, gaining velocity and hurls it at a goblin away from Sildar.

Magic Stone: Attack: 10 Damage: 8

While still remaining in the shadows, Feu casts Fire Bolt, targeting Goblin 5.

Attack: 13 13

Damage:  7

While Paren's foot connects with the leader's ribcage and nearly knocks him out, Rweni's stone whips past a goblin head harmlessly. Attacking from around the corner, Feu remains unseen, but their fire bolt only hits a stalagmite by the goblins.

(Please roll initiative, everyone. Surprise round is over.)

Initiative: 20

Initiative: 15

Paren Init - 16

(You all go before the goblins. Round 2! Paren or Feu, then the other, then Rweni.)

(Paren can act first, in fact, I think it would make more sense if the one with the higher dexterity acted first when two of us get the same initiative roll.)

Since the leader is still up; Paren will target the leader than the next goblin once leader is down.

Hand: Attack: 18 Damage: 5

Foot: Attack: 25 Damage: 8

The leader goes down with a grunt, but the other goblin bats away Paren’s attack with his shield.