John Yoon

First of all you need to explore all the skill available in the default wc3.
From there, you can make you own skill that might related or solve your problem.

How to increase unit armour
There are several skill can increase unit armour such as inner fire, scroll of protection (not sure the name but it can heal unit and increase armour temporary).

Dota circle of power is actually make the unit invulnerable and omni knight ultimate make the armour to 9999 (not invulnerable).
There is an action inside the trigger "unit-make unit invulnerable" or simply use the human paladin hero skill.

Well, i have also 1 another abandon idea ( not project )
The idea base on the meele game + risk game from wc3

Base idea :
You can conquer a town and build an army and then go for war.
Town is invulnerable, you can only capture them.

Want to try that?

Well, currently im try to make an RPG game. But i also have some abandon (not really abandon) game idea if u like.

The abandon game is like an Orc gladiator game but this time its a custom hero.
But this is actually not that easy and cant be consider as mini game

And my current RPG game is
http://www.thehelper.net/forums/showthread.php?t=117139&page=4

Simple mini game usually will be no computer involvement. Its a player vs player game most of the time.

I already review you game and the game is too simple.
Its okay if you still new with the wc3 editor. (Im also not really good actually)
Take your time to learn and create more mini game.
Creating large game (usually RPG) alone not going to help much for learning.