I have to disagree about the dota allstars AI being any kind of reasonable challenge- besides being newbish opponents at best, they make a couple of particularly huge and fatal mistakes which it would be wise to have your AI avoid:
1) They don't fear opponents who have crushed them before. They therefore will suicidally attack an opponent they have no chance against again and again and feed tremendously (I've played 1v5 games where I ended up with 200+ kills before finally making my drive for their ancient). I would suggest adding an if/then to your triggers checking how many times the AI has been defeated by a nearby foe vs how many times the AI hero has won. Have them flee or call for reinforcements if they ever have 2 more losses than wins and definitely flee if it looks like they're about to fight against 2 or more healthy opponents (maybe sum the % life of nearby enemies to check that.
2) they prioritize denies over last hits, leaving them impoverished. Every guide for every hero basically says you should focus on last hitting over denying; the AI just hasn't got the memo. This might or might not actually be a thing in your particular game.
3) They don't use the buddy system and are therefore easily divided and conquered. One major problem with WC AIs in almost every map is that it's easy to aggro just one enemy, lure it out alone, and murder it. Make your AIs run to group together with allies nearby if attacked alone. And make it so if one AI hero aggros onto an enemy, other AI heroes will approach and try to help.
4) They just do a ton of wholly useless and terrible stuff like jungling for huge amounts of time late game or running back to the fountain a lot to buy items.
The dota allstars AI tries to make up for this by cheating heavily, gaining huge bonuses to XP and gold unless you turn that mode off. This kind of AI crutch is to be avoided if possible. It won't really disguise a weak AI from any but a novice player. If you need to beef up your AI, I suggest using their strengths: impossible reflexes and calculation speed.