When you go to the Menubar and click on the Utilities -> Game File Operations -> Unpack Game Files button, a window like the one on the right will open up. This is a list of most of the game files - all the most commonly needed ones, at least. Each of these .pak files correspond to either a featureset of the game, or a patch. But which ones matter to us?

The following files contain visual assets that are useful if that's what you intend on working with: Assets.pak, Effects.pak, Icons.pak, Materials.pak, Models.pak, Textures.pak

Game: Contains UI-related files, Scripts, and more. Very much worth unpacking.

Gustav: Contains files with the Larian-specific Definitions for the game. This is a must to unpack.

Shared: Contains files with the 5e-specific Definitions for the game. Almost all our spells, races, classes, items, and more are stored here. This is a must to unpack.

English: Contains the English Localizations files. Extremely useful for manual searching of the game files when the Index Search doesn't fit the bill.

day0, Patch0_Hotfix1, Patch0_Hotfix2, Patch0_Hotfix3, Patch0_Hotfix4, Patch1, Patch2, Patch2_Hotfix1, Patch2_Hotfix2, and on and on. These, of course, override anything in the other .pak files.

If you have the space, it's recommended to hit the Select All button, but if not, You'll want to tick some of the above mentioned files. When you've made your selection, hit Confirm, and buckle in for a wait, as the Multitool will now start unpacking the files into a Folder next to it: \UnpackedData.

Once the process is complete, you'll see the following folder:

When you click into it, it will look like this: