Big post incoming!
I've had some thoughts of making an AOS, got some pretty neat ideas from other members here and from my own mind, i will quote them and copy paste from my development thread, do what you want with them, i found them useful for my map at least, was some nice things to add

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My own ideas:
-Upgradeable creeps and towers
-certain points that give exp/units/gold when controlled that exist on different spots of the battlefield
-Abilities to some of the creeps
-Sending bomb attacks at a point in the map, ground as sappers, when they reach the target they explode and deal some damage (needs to be timed very great to be nice) or as zepelins, bombing units below them.
Events- Well, random events, all heroes gets freezed for a couple of seconds, every hero gets some extra gold, every hero gets experience, random monsters spawns all over the map, all heroes takes 25 % of its max hp in damage, all heroes gets healed by 20 % of its max hp, all heroes gets a movement speed buff for a couple of seconds, Etc. Etc. Uncountable number of different events that happens at random times during the game can be invented.
Quote from Yeeshadow's post:
"- Another resource: I named this resource "magic", you used to buy special things, specially upgrades or to repair buildings (And something more importnat). The way to gather that magic was simple, there were lanes, each lane had one tower that produced magic, of course you could conquer those tree places to work for your side, it was a battle for resources too.
- More gold income: It worked like the magic, but instead a tower, it was a gold mine...
- Summon Builders: No, no, this is not a common hire peon-type unit to use it to repair your base, you buy that thing to summon lots of peons to repair the towers. I really loved how it looked, a lot of peons appeared in front of the castle (the primary building you need to destroy to win) and they start running all around repairing towers, buildings and almost everything. Of course you could kill the peons to stop them.
- Power Generators: The goal was the same, destroy the enemies base, to do that, you needed to destroy the generators first, those generators were almost in the entrance of the base, to make it simple... but, this was to make people fight in each lane, not just focus on one.
- Rebuild Buildings: You could rebuild your defenses and of course the generators, for that you needed magic. This worked different from the Summon Builders function, the buildings just appeared (with a teleport effect) so it was an instant thing, this is a very tricky part for the balance, but it make the game really fast, always with lot of action, you needed to be fast to defeat your enemies, this simple function make the map 10 times more interesting, and you need to destroy the enemies magic spots as fast as you could to prevent them from gathering magic.
- Change sides: What?? Are you insane?? Yes... you could be a traitor the whole time...
- Send items: I loved this function, if you are a terrible player you could send items to the other players to help. Lets say you buy a potion and want to send it to another one, you go to the shop, "buy" the send item, you give the item to the runner, and she started running, the problem is that she could be killed and she dropped the items.
- Nightmare Spell: Well, this is as simple as it sounds, but it was extremely weird, it was an ultimate, you put to sleep a target then it becomes invulnerable, then a ghost appeared far away from the target, that was a representation of the unit dreaming, that ghost could be controlled by the owner of the sleeping unit, the objective was to reach his body to wake up, but, if the ghost was killed before reaching the body the sleeping unit died, the problem is that the only one that could see that ghost were the nightmare caster, but the ghost make the minimap ping, but if he stopped, the mini-map stop the ping, so it was a hide and seek mini-game with an ability. I never uploaded this because is harder to use than it sounds, specially beacause you can't make the ghost appear in any place, because it could get trapped.
- Advance AI: And it was seriously Advanced, so advanced that you could only use it in single player mode (too much lag in multiplayer, specially with full house, 10 players). And what is the advanced thing? Well... if you typed something like "I need gold!" or "Gives me money" or things like that, the AI
respond in different ways, so, it was really AI, not a simple command, like "-all gold to me". Let me get a little more in depth with this system.
- Each hero have their own personality, and each hero react different depending on the situation. You may have seen things like, the base is being destroyed and the AI is still trying to destroy the enemies base... well, with my system the AI, depending on the situation and the personality of each hero they could go and defend, buy a "Summon Peons", continue attacking, and more...
- More important, the AI was created to make the player feel like it was playing with someone. Not just another random creep. If you typed things like "help me", they answer depending on the situation and their personality, and yes... they answer... They could answer things like "Can't you see I'm in trouble here?" or "Can't teleport, I'm going as fast as I can", each hero with more than 20 different phrases for each situation...
- To make the player feel like it was playing with someone else, the AI also talked sometimes, and can even chat with the other AI units, from your side and from the enemies side too, they could something like "you're gonna die" or they could ask for your help, money of something else, like "I'm dying here! Please give a potion, you have to spare!"
- To make this possible you need to develop the heroes, their history, an more, it was really simple to me, because they were from a previous campaign I created, so they act as if you were playing with those characters, they even have a relation between heroes that could change their answers.
More things that are not really common but have been used:
- Upgrade units: Stats only
- Upgrade units: Change their actual look and improve all their stats.
- Quests"