Just bought this game, played through the first chapter then a few custom games. every time felt like the same game on different terrain. So I figure the funnest part must be the modding. I read through the modding guides 1 and 2 and browsed over the tips on the rest of them below that.

So I found out after reading all the stuff how to create a new campaign, and make intro movies with the .bik video format and items and heroes and icons for custom artwork and what not. Im still confused on how to direct a story in the campaign, I see from the first campaign the xml file has npcs that show up and talk, I dont see how they placed blocks on the map to prevent players from going to far ahead of the story or when preciesly to spawn a group of specific units just that the units are outlined in the xml file but not actually given a command to spawn during certain timelines events.... I just dont see anywhere how thats happening with the MaincCampaign.xml file and obviously would all be huge parts  of helping drive a story or hold it back. 

For example if I wanted to do lets say.....

Hero passes through a specific tile on the map that on the first time only it triggers a unit to spawn directly behind him gets a free attack against the hero and then initiates a combat sequence that you cant escape from.

Or a different example...

Villain of the campaign has just been beaten, spawn a new copy of the villain that starts at 1 hp to represent that the villain wasnt slain just basically beaten to crap. a short dialog ensues and of course we will go with the cliche that the villain isnt beaten at all and powers up with full hp and reveals his true power, blah blah blah. so we wipe the villain with 1 hp off the map put a new villain on the map with full hp and better stats.

For the second oen i know obviously Id need 3 different unit's laid out in xml for this one character, one unit that has its normal stats the next that has like a 1 in con and then the last being the powered up version. The question basicvally is how do I take away and add units at my whim and exactly when and where i want them?

For the most part i understand this all, I just need a little help to get me in the right direction.