Age of Mythology: Retold

This is an easy achievement.

Start a skirmish with the Norse using Thor
Settings:

• Standard Mode
• Game Speed Fast
• Infinite resources
• Reveal all
• 1v1

Start:

1. For this, do not create any Berserks and do not convert Dwarves to Berserk as they may be classed as Infantry. So you can only use the one builder Beserk that you start with.
2. Begin by building the temple and then upgrade to age 2 and be sure to choose Frejya which will safely give you a cavalry hero. No more age upgrades required beyond this point.
3. Build all houses to allow for max troops/units.
4. Set your temple to auto create Hersirs and if required build more temples to allow you to create Hersirs at a faster rate. Upgrade Hersirs at the temple if available.
5. Once you have a large Hersir army, go ahead and destroy the enemy base to win the match and gain this achievement.

If you need more help with this you can follow my video guide below which will begin at this achievement:

I just now did it in about ten minutes. Start a skirmish with one AI on lowest difficulty. Set ressources to infinite. If you are comfortable with it, increase the games speed. I choose Loki, but you can take anyone. If you are comfortable with it, set game speed to high.
At the start and build a temple, go to the next age and build houses.
Once you reach the second age, auto-queu Hersirs, built a forge, advance to the next age, build Longhouses (5-10) and start building additional towncenters. Upgrade anything improving Hersirs.
Once you got that done, built a fortress, advance to the fourth age.
Now when you have about fourty Hersirs, attack-march them into your opponents base. They should not need any supervision.

The AI never attacked during the buildup.