SC2Mapster

Any ideas on how to construct such a passive ability?

If Shield armor is greater then or equal to damage dealt, then no damage is dealt to said unit.

Fear not fellow SC2mapster member, it was quite difficult to make it work, but i have the solution you requested!
Description: the Behavior does not do much on its own. you need to go to the Triggers, you will find the actual "passive ability" of yours.
Link Removed: http://www.mediafire.com/file/4qzcsjvdulr1bko/onlyleviathan-totemhokem_HeavyPlating.SC2Map/file

Edit: you can just launch the map to see it in action for yourself, Triggers are setup ready for testing.

 Hmmmmm.... Interesting trigger solution, although it could be lag inducing in a larger game of 12 players with team fights and abilities. 

I do appreciate it, however, if anyone else has ideas for a DATA solution I would also be interested.

This is for a single unit only.

Armor and effects are all upgradable.... and there are dozens of abilities from other units that may add or reduce armor and add or reduce damage.

 As much DATA as I can use would be my preference. I see now the trigger event you can use from damage response. But rather then simply firing a trigger every time my unit takes damage, would there be a way to determine the amount of damage so that the damage response only fires when the damage is equal to 1 or less? 

If that is possible then I could simply use the ignore damage modification field and then the response would only fire when the damage is 1 or less. This way armor is irrelevant since in the case the unit takes 1 damage, that would mean its armor is already equal to or higher then the damage being dealt and the response would fire appropriately to ignore said damage.

How about the Damage Response Max Field? Simply set to 0.5 and it seems to do the trick. Only actual draw back is when dealing with armor piercing effects. 

EDIT:

I just found this now, was reading about it in the wiki. It states

Combat: Damage Response - Maximum

Only damage below the value triggers a damage response.

The weird thing is in testing, it's not 100% accurate, but its pretty close to the effect I desire. For example, if a unit attribute bonus damage, it doesn't seem to take that into account. 

Lets say the unit with the passive has 3 armor and I attack with another unit that is dealing 2 damage. It works! I then upgrade the damage amount to 3, still works. But if you give the damaging unit an attribute bonus of +3 to massive (buffed unit is then set to massive), the damage response still won't kick activate until you take the base damage amount to 4. 

Sorry about that, I was mistaken. I setup a trigger to test what damage was actually being dealt. It appears now that it is all working correctly, including the attribute bonus. 

I think this solution is far cleaner then using a trigger solution and its quite easy to setup in the damage response field. Since armor and damage values are constantly changing, any time the unit takes the minimum damage from the Default game value due to high armor, the damage response will trigger and it will ignore the damage! 

Works like a charm, except won't technically work with armor piercing effects.

Thanks for the help everyone. Sometimes you just need a few ideas and postings to get the brain going.