There are 2 main parts of the strategy. I use only base game units/buildings without the DLC, so that anyone can do this.

1. Guard Post AI trap: Guard posts can be upgraded 5 levels, and each level adds more troops. It appears the AI doesn't account for the number of guard post troops, but it does prioritize attacking towns. This means if a town is empty but the guard post is level 5, it attacks the guard post regardless to reach the town. Since the AI doesn't look closely at guard post strength, we can use this to create a trap.

2. Exploiting racial bonuses: Horn-Bowyers are a T3 Pillar ranged unit with special abilities. Beast Slayer means it does 150% damage to Beasts, and Long-Ranged increases it's arrow range. We pick Enclave as the enemy AI, since all it's units are beasts. This way, your archers have a 150% damage bonus on the AI's entire army and can hit them from farther away, too.

The strategy is pick Pillar, Enclave for the AI, build a small army, then upgrade the guard post. Around day 6 or 7 the AI attacks the guard post, gets annihilated, and then you blitz them before they can recover. It's pretty simple. Due to the AI pattern it always attacks the guard post in my testing. The mass of Horn-Bowyers and other units in the upgraded post easily slaughters the AI army for you.

Of course, none of this strategy would work without manipulating the game settings to gain the greatest advantage. Hey, this challenge is completely unfair, so why not even the playing field?

- Map: Duel. We need to be very close to the AI so they attack in week 1 or 2.

- Hero: Any. I've done this with every Pillar hero. The hero power doesn't make that much of a difference for a short game. (Note, if you pick Tono and build a Mercurial regiment, this may cause the AI to delay their initial attack by a few days). For the Enclave, I pick Olane.

- Starting resources: High. Gives you everything you need

- Hero movement points: High

- Guard difficulty: Low. Lets you capture the guard post week 1 without problems

- Unit creation cost: Low

- Unit growth modifier: High. For a bigger army

- Building requirements: Low

You don't need to fight any neutral camps except the guard post. With starting resources set to High and buildings/unit cost to Low, you have all the resources you need. Remember this guide uses the base game buildings, no DLC.

Day 1: Build a Pagoda of Heaven. Pick up any XP bonuses on the map, enough for your hero to reach level 2.

Day 2: Build a Shrine of Beasts and choose Pan Da.

Day 3: Build a marketplace

Day 4: Build a Hall of Crafts

Day 5: Build the Upgrade Center, upgrade Bowyers

Purchase all available Pan Das and Bowyers, then attack the guard post. It should fall with minimal losses, and your Pillar hero can use creature saves (Union for might heroes, Balance for magic heroes). After defeating the guards, upgrade the guard post to at least level 3. Level 5 is costly and unnecessary. If you're low on resources, you can buy more from the marketplace.

That's it! All you have to do now is sit back and wait for the AI to attack the guard post. It's early army will be totally wiped out by the upgraded post. The default battlefield puts your melee units outside the fort walls for some reason, so make sure to move them inside before the battle begins. This gives your archers more time to soften the enemy up a bit.

Note: Don't build a Fort or Plaza. These buildings cost a lot of wood/ore, aren't necessary to win, and can hinder upgrading the guard post.

At this point, you can just march into the AI territory and take their town. They don't have an army to stop you. You should have plenty of gold, so buying wood/ore for a catapult to siege the town makes the battle easier, but isn't required.

If you can't reach the town by day 7, wait for the 2nd week units to resupply before attacking.

There are plenty of variants to the basic strategy, as long as you capture the guard post around day 4-5 to trap the AI so it loses all momentum.

For example, you can attack the neutral camps for XP and wood/ore to build a fort and more Bowyers, or the gem camp to upgrade the Pan Das. You can also buy other units and expand your army, if you want to play with your food before eating it. However, the variations are superfluous and not required to win, so I kept the guide as simple and easy to follow as possible.