Warcraft 3 LAN Game discovery

The Warcraft 3 Editor uses campaigns to share data between multiple maps. In your case simply create a campaign and then import all data (units, triggers, whatever) from the map into the campaign. Then, if you add any other maps to the same campaign you can export data from the campaign out to your other maps.

The only trick to this is that importing and exporting copies data; changes you make in one place will not be reflected in others. So be careful to update your changes in all maps and the campaign if you want to be consistent! The best practice is to make changes to the campaign and then push the changes to your maps: that way you know that the campaign always contains the most up-to-date data.

You are in luck! Blizzard has been including cheat codes in its games since the original Warcraft: Orcs and Humans.

Among the cheat codes available for Warcraft III is the handy level-select cheat:

The "Motherland" "Race" "Level" cheat is what you're looking for, so to skip to the beginning of the undead campaign, enter any campaign mission, and enter the following in the chat box (accessed with the enter key):

Motherland Undead 1

And you should be well on your way to Deathknight-ing it up with Kel'thuzud.