Expert Prerequisites

Basically all the previous prerequisites. See Beginner, Intermediate, and Advanced prerequisite guides first.

IDE is absolutely required

Without an IDE, your chances of success in these tutorials is slim. Once again, we recommend installing the latest Visual Studio Community. It is free and fully featured. Visual Studio Code is also possible, and can also provide Intellisense and debugging functionalities.

Debugging

You must know your way around the debugger. You need to know how to use breakpoints and inspecting values in break mode. The guide for setting up Visual Studio correctly is here. The very best setup for debugging is when you also have the tModLoader source, this way you can step through the code as it shifts between tModLoader code and your mod's code.

tModLoader Source code

You may need to decompile tModLoader to understand the correct way to do something, or to figure out the recommended approach to what you are doing. Anyone attempting to do Expert level guides needs their own copy of decompiled tModLoader.dll. The best way to get this is to download the tModLoader repository and run setup. This will net you a completely functional solution that you can open in Visual Studio. Another way is to download ilspy, explained in Advanced Prerequisites.

Experience

By far the most important is experience. A college degree (in Computer Science), previous mods you have made, and a knowledge of c# will all help you tackle Expert level topics.