LuaTrig is a program to write Age of Empires II triggers in Lua scripting language.
Why is this so awesome? Well, making a big series of triggers is super easy now, because we have a full scripting language at our disposal!
You can use this program in two ways. The easy way is to just create a trigger in a scenario, then export the scenario to script and edit the triggers with copy/paste of text.
Or you can use the power of Lua scripting language... See some example code of 'lua-power'
The more advanced stuff takes a bit programming knowledge. But if you can get this, making big sets of triggers has never been easier.