I found how invincible army works i had the same problem.To make it work you must be in map and the select one unit so the trainer can capture health value THEN you must activate the option with num 6 and its all ok.When play skirmish match better do not activate instant building bacause you will be unable to win the match.Have good Gaming.
If I just do it for one unit on the map will all my units be invincible?
Yes all units and buildings too.I have test it in campaign and in skirmish match and it worked.Just be in the match click on one of your unit anyone and then activate the option.When the match end i deactivate it and for the next map,match i activate it again.It always works this way.Have fun im glad i could help
I just want to make sure that I get this right. when I am in game where the battle takes place I am supposed to activate the option. And when exactly am I supposed to deactivate the option?