Went immediately for the murlocs with the boots, came back to fight off waves from both enemies, went north to attack the towers and slipped a peasant through to build the town hall. Attacked purple base with a group of footmen/riflemen/priests/mortars @ about 65-70ish supply, took out most of it before I had to come back to defend (though peasants did pretty good as militia against one weak wave). Keep in mind that if you get attacked you can draw the aggro of the attacking force with a single rifleman or something and then just run around a bit.
Sadly I was not able to beat the green base. It has a level 10 lich (2 frost novas will essentially destroy an entire army) and a lot faster production (3 crypts 2 temples 2 slaughterhouses vs. 2 crypts 1 temple 2 slaughterhouses). I suspect it might also be getting some cheats in the final minutes to turn up the pressure. The rate that it can churn out units and re-summon their hero is very hard to press through. I killed the lich while attacking the base, killed a few structures, kill the Lich AGAIN, then as I was barely able to keep up with the production from the green base he came back again and just raped me. Just to give you an idea of my army composition the final group I used for the attack had 8 footmen, 8 riflemen, 8 priests and 7 mortars. Not because I was fixated on the number 8 but just because that was what I ended up with.
In retrospect:
- Arthas not having level 3 holy light was a mistake, you really want that to kill those liches. I was level 2 holy light level 3 devotion + resurrect, but honestly resurrect is useless since you'll generally get only 2-3 units out of it (if that, necromancers tend to steal your corpses especially with how many the 2nd base has), and a level 2 or 3 holy light is basically a full heal anyway. Load up Arthas with 1-2 potions of mana and take them out quick. Level 3 would also one-shot necromancers which would be a pretty good deal, get more mana potions.
- Priests are kind of crap for their healing once you run into the disease from the abominations, considering they can't get master rank training to improve their mana gain and there's no good mana fountain (and the healing fountain is far enough away as to be useless). Just having 2-3 priests mainly for dispel (keep healing disabled until you need it) rather than 6+ and a ton more riflemen in their place is probably better, at least if you want to take out the green base and try to keep up with the rate it spams units. I did forget that riflemen countered heavy armor in original WC3 until I was done with the mission.
- Similarly I forgot that mortars actually do reduced damage to casters in WC3 rather than increased like in TFT. Its still kind of fine though, they tend to be the only units that can reach necromancers and they'll take them out in 1-2 volleys, and since AI necromancers always clump up for your AoE you'll be able to kill them pretty quickly. Its also useful for skeletons/ghouls/meat wagons. It's also notable that they'll clean up the liches pretty well, despite only doing 50% damage that's 50% of a fuck ton vs. the absolute shit damage footmen output. With 6 mortars you should be able to take him out quite quickly in conjunction with level 3 holy light.
It's basically impossible getting the expansion on March of the Scourge and keeping it. It's easy to get it, but the undead attack it relentlessly and you have to split your forces, something you can't really afford on hard.
lolok. But seriously, if you aren't taking out purple like I did then just station your army around where the purple towers were, you can basically zone out attacks to the expansion while quickly responding to attacks in the south. I didn't build any towers, I just scattered some farms on the southern entrance to the main base (DON'T put them right next to each other or the AoE from wagons will take them out much quicker). Sure you might lose a farm or two before getting back to defend but that's trivial compared to having a whole second base.