So would it look more something like this or-?
I think I understand what you mean by the 2nd part now, the 1st part is still a little cloudy for me
Trying to follow with you as much as I plausibly can I'm having a bit of troubles though.

Code (Skript):

1.  
2.     set {_item} to slot {slot::%player%::%event-slot%} of current inventory of player
3.         loop all items in player's current inventory:
4.         set {_i} to 0
5.             loop {_l::*}:
6.                 add 1 to {_i}
7.                 slot {_i} of player's current inventory is not ender chest named "&6&l???" with lore "&7Click to redeem a random item" and "&7from the Irothai Caverns&7 Lootbox!":
8.                     name of player's current inventory is "&lIROTHAI CAVERNS LOOTBOX":
9.                        set slot 49 of player's current inventory to glowing chorus flower named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!"
10.                        stop
11.  

Also I read up on this about the different types of variables and I understand them a liiiiiittle better?
Here's the link if anyone wants it http://en.njol.ch/projects/skript/doc/variables

--- Double Post Merged, May 26, 2019, Original Post Date: May 26, 2019 ---

I realize now that the numbers in "slot (numbers) of player's current inventory is ender chest name..." should probably have been changed to {_i}, edited above ^^ correct me if I'm wrong

 

Oooh, no problem! Thanks I've give it a shot and let you know if something happens

--- Double Post Merged, May 26, 2019, Original Post Date: May 26, 2019 ---

Code (Skript):

1.  
2. set {_i} to 0
3.     loop {_l::*}:
4.        add 1 to {_i}
5.        slot {_i} of player's current inventory does not contain ender chest named "&6&l???" with lore "&7Click to redeem a random item" and "&7from the Irothai Caverns&7 Lootbox!":
6.            name of player's current inventory is "&lIROTHAI CAVERNS LOOTBOX":
7.                 set slot 49 of player's current inventory to glowing chorus flower named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!"
8.                 stop
9.  

So like this?
If so it gives an error:

Can't understand condition for "slot {_i} of player's current inventory does not contain ender chest..."
"slot 32, 31, 30, 23, 22, 21, 14, 13 and 12 of player's current inventory does not contain ender chest..." also didn't work with & w/o the {_i} and {_l::*} variables, gives same error

EDIT: ah wait nevermind I assume you mean

Code (Skript):

1.  
2. loop all items in player's current inventory:
3.     player's current inventory does not contain ender chest named "&6&l???" with lore "&7Click to redeem a random item" and "&7from the Irothai Caverns&7 Lootbox!":
4.         name of player's current inventory is "&lIROTHAI CAVERNS LOOTBOX":
5.             set slot 49 of player's current inventory to glowing chorus flower named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!"
6.             stop
7.  

Not the other one I sent

 

Right that worked! Awesome! That issues taken care of now the last thing is the stuff I wrote for giving the items to the players isn't actually giving it to them, any issues you see here?

Code (Skript):

1.  
2. set {_item} to slot {slot::%player%::%event-slot%} of current inventory of player
3.  

Code (Skript):

1.  
2. on inventory close:
3.     name of player's current inventory is "&lIROTHAI CAVERNS LOOTBOX":
4.         loop all items in player's current inventory:
5.             slot 32, 31, 30, 23, 22, 21, 14, 13 and 12 of player's current inventory is ender chest named "&6&l???" with lore "&7Click to redeem a random item" and "&7from the Irothai Caverns&7 Lootbox!":
6.                 wait 1 tick
7.                 give 1 ender chest named "&4&l-=+> &c&k::&7 Irothai Caverns Lootbox &c&k::&4&l <+=-" with lore "&7A mysterious box found in the depths of", "&7the Irothai Caverns, there may be more", "&7down there, but this is the first of it's", "&7kind to see the light of day...", "&k", "&f&lNORMAL REWARDS:", "&7 - x32 Diamond Blocks", "&7 - x256 Bottles of Enchanting", "&7 - x2 Beacons", "&7 - x1 Irothian Pickaxe", "&7 - x64 Golden Apples", "&k", "&5&lEPIC REWARDS:", "&7 - &5x1 Reward Loot Crate &7(Tier 1 - 3)", "&7 - &5x2 Enchanted Golden Apples", "&7 - &5x1 Shulker Box", "&7 - &5x1 Mending Enchanted Book", "&7 - &5x3 Random Custom Enchants", "&k", "&6&lLEGENDARY REWARDS:", "&7 - &ex3 Random Loot Crates &7(Tier 2 - 4)", "&7 - &ex1 Experience Booster &7(4 Hours)", "&7 - &ex1 Command Access: &7/sethome, /home", "&7 - &ex5 Random Custom Enchants", "&7 - &ex1 Dragon Egg", "&7 - &ex1 Elytra", "&k", "&4&lDIVINE REWARDS:", "&7 - &cx1 &k::&7&l Irothian Knight VKit Access &c&k::", "&7 - &cx1 &k::&7&l Irothai Caverns Key &c&k::", "&7 - &cx1 Potion of Unlimited Buffs &7(3 Uses)", "&7 - &cx2 Totems of Undying", "&7 - &cx1 Random Divine Custom Enchant" and "&7 - &cx1 Admin Item" to player
8.                 stop
9.             slot 49 of player's current inventory is red stained glass pane named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!", "&k", "&4You must open your main rewards before" and "&4you can open your &nDIVINE&4 reward!":
10.                 wait 1 tick
11.                 open event-inventory to player
12.                 stop
13.             slot 49 of player's current inventory is not red stained glass pane named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!", "&k", "&4You must open your main rewards before" and "&4you can open your &nDIVINE&4 reward!":
14.                 slot 49 of player's current inventory is glowing chorus flower named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!":
15.                     wait 1 tick
16.                     open event-inventory to player
17.                     stop
18.  
19.  
20.             slot 49 of player's current inventory is not red stained glass pane named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!", "&k", "&4You must open your main rewards before" and "&4you can open your &nDIVINE&4 reward!":
21.                 slot 49 of player's current inventory is not glowing chorus flower named "&4&lDIVINE REWARD" with lore "&7Click to receive a guaranteed", "&6&lLEGENDARY&7 tier reward or higher!", "&k" and "&6Legendary&e and &4Divine&e reward", "&echances are increased!":
22.                     {_item}
23.                     stop
24.  

(I separated the part of the code that I wrote in this 2nd code block that is supposed to give the items to the player.)
(Gives no items, not even 1. No errors)

 

oh my goodness what is wrong with me right now.
I'm so sorry

 

I set "{_item}" to

Code (Skript):

1.  
2. give {_item} to player
3.  

and that didn't work

Also the set event is above the thing that checks if all 9 ender chests don't exist, didn't add it to the code block when I sent that, sorry for that

Code (Skript):

1.  
2. set {_item} to slot {slot::%player%::%event-slot%} of current inventory of player
3.  

That's what I set it to ^^

EDIT: Currently working on the code from scratch with TPGamesNL and AsuDev (Revelationage) via Discord and will post the finished result on the thread so people can see how it looks and what I changed to resolve the issues on this thread, might take a little but if possible don't kill the thread until I post that update, thanks~