Hey guys, mind if I join the conversation...?
I've had an idea few weeks ago (didn't know about this map back then) about how to make a decent "difficulty system"... I've also told CloudWolf about it, but I'll post it here as well, if it's okay (well, as it is already here, I don't seem to care about whether it's a problem or not)!
In this system, monsters could have more increased abilities, not only max HP... For different modes, you would need different spells. Let's see an example: attack increase. For this, you would need to create 2 different spells, they could look like this: Attack - Medium (for the 2nd difficulty, this would increase some attack of the monsters), and Attack - High (this would be made for the 3rd difficulty, the hardest of all, with an even larger amount of attack). There's no need for Attack - Normal, as the monsters' current attack would be good for the normal difficulty. Spells could be really different for every mode, you could even add defense, HP (I think it's a lot easier to do it with spells, not with handicap), HP regen, even some evasion!
Triggers wouldn't be that difficult either... The first thing would happen at map initialization (but you will also have to add another thing to the event, which I'll mention later): it should count how many player slots are active (so basically, it'd count the number of players in game). There would be a condition, so you'd need 3 triggers for each mode (or an if-then-else action). The first trigger would look like this (after looking at your latest posts, I have a picture of how you wanna do it): event was already mentioned, condition would be an integer one - number of playing players must be above 4. The action would be following: take every spell that you would add for the 2nd and 3rd difficulty level. For the other difficulties, you will have to do quite the same, but this time, you must include adding your picked difficulty's spells to the units (pick every unit owned by the "AI"). The 3rd difficulty (I'll call it hard) would look like this: less than 3 people in game, add the "X - High" named spells to the picked units, and take the "X - Medium" spells from them. Guess you have a picture about "normal" mode now, as well.
I've talked about mentioning something important about the events - here's the time: you must add something to the event that will make the trigger work, once a player leaves the game or runs out of "lumber" (this can be done in conditions I guess). So if a player leaves the game with a victory or defeat or whatsoever (can't really remember the options, hope you get what I'm trying to say anyway), it should count the players again and add/take the correct spells to/from the monsters owned by the bot.
Guess that's all I wanted... You have to know that I haven't read much in the forum, neither have I checked out the website, so I dunno if there were already people talking about this, sorry. I only hope that this helps in some way. Good luck with your system, I hope you won't hate me for this long post so much, so I can stay here and keep checking your ideas and posting mine!