The larian wiki is the place to start if you want to learn how to mod the game.

https://docs.larian.game/Category:Osiris
https://docs.larian.game/Scripting

Of the three scripting languages I would focus on Osiris or Lua. I use Osiris 99% of the time over character / game / item scripts. My mod is like 20k lines of osiris script and maybe 200-300 lines of game script. I don't have the coding background to get into Lua but it from what I here superior to the other 2.

You will definitely want the script extender
https://github.com/Norbyte/ositools/releases

and probably the VsCode + extension that allows you to compile your osiris script, called story, in VScode.

https://marketplace.visualstudio.com/items?itemName=sebastian-lenz.divinity-vscode


The Divinity Discord is a good place to ask questions. But I would recommend first learning what you can from available resources first. Another thing you can do is unpack mods with the Divinity export tool

https://github.com/Norbyte/lslib

Unpacking others people's mods is a good way to see how various functions work. I would open up all the scripting from a few mods in Notepad++ so I could search all of them for use of specific functions.

I don't know exactly how you want this barrel thing to work but here is some scripting that should 1) make a barrel when you use a particular skill at a location the first time it's cast
2) Move the barrel if the skill is cast again
3) If the barrel is destroyed the next skill cast creates a new barrel.

Thats exactly what I was looking for. Thank you