As Amiz climb's onto the wooden platform, he comes across three goblin's. Two of them are on the platform with scimitar's drawn, while another is just above near the controls for the platform holding a Shortbow. They yell in goblinoid and attack the Leonin. I'll roll initiative for everyone, although as the rest of you are below the platform, all you hear is a yell in goblinoid and the sound of battle above:

Group 1: Draíocht

Group 2: Goblins

Group 3: Amiz, Thelanis, Valar.

Draíocht is up, you hear Amiz encounter the goblins on the platform, but all you see is the platform above and the rope connected to Amiz hanging in front of you.

Draíocht heads towards the sound of battle. Once he sees the goblins he knocks an arrow and looses it at the goblin with a shortbow.

Action: Longbow Attack @Shortbow Goblin
To-Hit: 5+5 = 10
Damage: 5+3 = 8 piercing

A decent strength shot, but perhaps he was a bit hasty in rushing to the sight, not getting a good enough aim.

How does Draíocht get up to the platform? Amiz climbed up the side of the shaft with an Athletic's check. Becuase you are below the wooden platform, you'd not be able to see what's happening up there. So you wouldn't be able to target them with an attack.

[[ Ah. Was thinking there'd be an angle to shoot at them from below. Would readying an attack on one that comes towards the edge be possible? Otherwise he'll turn to Valar and cast guidance upon the paladin, realizing that he himself is not the most athletic to quickly traverse upwards in a heated situation. ]]

I'd say guidance would be more helpful than readying an attack. Although it is your character so you choose. For now i'll assume you cast Guidance on Valar.

Back on the platform, the two goblins slice at Amiz while the one up top shoots with it's bow:

Goblin 1 Scimitar against Amiz Attack: 8 Damage: 3 Slashing

Goblin 2 Scimitar against Amiz Attack: 22 Damage: 3 Slashing

Goblin 3 Shortbow against Amiz Attack: 23 Damage: 4 Piercing.

You all are up. Dedear will offer to give Valar a boost up the rock wall. Offering Advantage as well as Draíocht's Guidance in his efforts.

Amiz growls as an arrow found its way into a gap in his armor.

He uses Daunting Roar as a bonus action.

all the goblins need to roll Wis Save DC 13. On fail they are frightened until the end of my next turn. 

Main action he unties the rope and ties it to the platform "Come on up I found some company" 

Nice, although if you want to tie it up in a single turn, i reckon you'll need to roll a DC 10 Sleight of Hand Check. Because doing so under pressure within 6 seconds would take a little bit of work.

Here's the Goblin's WIS Saves

Goblin 1: 1

Goblin 2: 6

Goblin 3: 18

The two Scimitar wielders are petrified of you, but the shortbow user seems to be holding itself together.

Valar will try to climb up and assist on the platform: Athletics 17

Amiz 

Sleight of Hand

19 - rolled in game log. Have advantage due to rune knight feature. 

[If Thelanis has line of sight to anywhere above the platform, and it is less than 30' up...]]

Thelanis points her sword at the platform and vanished in a flash of purple light, only to reappear in front of the shortbow wielding goblin, attempting to run it through.

Bonus: misty step
Longsword: AC 19, 6 slashing damage.

[[Else]]

Thelanis will climb up herself, (Athletics 21) and make the above attack.

Casting Misty Step allows Thelanis to climb to the platform and attack Goblin 1, cutting him a gaping wound. Valar, with Dedear and Draíocht's help, climbs onto the platform too, ready for the next round of combat. The scimitar goblin's are still petrified of Amiz but attack anyway, there swords wabbling as they shake. The shortbow goblin above aims with a stable arm, yelling in Common "Die lion scum!" It looks at the platform controls next to it and smiles wickedly, taking it's shot at then moving towards a lever, about to to pull.

Goblin 1 Scimitar against Thelanis Attack: 7 Damage: 8 Slashing

Goblin 2 Scimitar against Amiz Attack: 9 Damage: 7 Slashing

Goblin 3 Shortbow against Amiz Attack: 7 Damage: 5 Piercing

You all are up. Three of you on the platform with the goblin's while another goblin is about to pull a lever above.

Thelanis continues her assault on the goblin.

Longsword: AC 13, 6 damage.

And you hack off the goblin's head. 

Amiz, Valar, and Draíocht are still up. The goblin at the control's is fumbling desperately now, about to pull the lever.

Valar will attack the goblin with the short bow: Attack 10 / damage 9

It’s about 10 fr above you. So you’d need to roll an Atheletixs check to see if you could get up.

Amiz wades in and attacks the Goblin about to pull the lever. 

Battleaxe

Attack: 18 Damage: Unable to parse dice roll.

With the platform getting crowded, Draíocht grabs the rope that Amiz tied up and tossed down to secure it on the down end too.

[[ Hoping that by tying it up at the bottom, that'll lower the DC of the Athletics check to climb up. ]]

Again, the goblin pulling the lever is 10ft above. Valar and Amiz will need to roll Athletics checks to get up there.

Amiz will chuck his hand axe instead at the goblin near the lever. 

Handaxe

24 to hit 8 damage- rolled in game log