Age of Mythology: Retold

Really easy achievement.

Start a skirmish with the Atlanteans using Kronos
Settings:

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

Start:

1. Begin by building the temple and then upgrade to age 2 using the town centre.
2. Next build an armory and then when upgrading to age 3 be sure to select Rheia as the god which will allow you to create Behemoths via the temple.
3. Build houses to allow for max troops/units and upgrade this troop type at the temple if needed.
4. Create multiple temples if you wish to create behemoths at a faster rate and then after creating a good amount of behemoths send them to an enemy base and allow the enemy to deal damage to them, in no time you will 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 seven minutes. Start a skirmish with one AI on lowest difficulty. Set ressources to infinite. Start with Kronos. If you are comfortable with it, increase the games speed.
At the start auto-queue villagers and build a few temples, go to the next age choosing Prometheus (he helps us speed things up). While that is happening, scout towncenters and build houses.
Once you reach the second age, built a forge, advance to the next age choosing Rheia, start building additional towncenters. Auto-queue villagers there as well.
Once you are in the third age, recruit 4 additional Behemoths (we got two from aging up thanks to Kronos). Just sent them to the enemy, they wont win, but you'll get the damage in easily.

I never got attacked once by the AI in the meantime.

Just use the in-game editor to create a scenario. Use place objects to place some behemoths for player 1 and behemoths for player 2. Save the scenario and the load it in skirmish mode. Run the scenario again if you don't get it first time round and its cumulative. You can do this for a lot of these achievement, just place the relevant units.