Age of Mythology: Retold

I just idled this in the second Atlantean scenario.

Towards the middle of it, you will be notified about a Greek base beyond a canyon. I placed Kastor in front of that wall and five Cladrias on behind him. He was constantly attacked by a trickle of enemies and the Cladadrias covered each other's cooldown, keeping him topped up. From the point I set it up it took about 15 minutes.
It didn't happen to me, but in case the Caladrias get attacked or Kastor is downed, I placed a large amount of archers just slightly out of range and put them on "Hold Ground". That way they would have slain anyone getting past Kastor, at which point I would have revived him and continued the idling. Was necessary, though.

This is an easy but time consuming achievement.

Start a skirmish with the Atlanteans using Oranos
Settings:

• Standard Mode
• Game Speed Fast
• Infinite resources
• Reveal all
• 12 AI Players

Start:

1. Begin by building the temple and then upgrade to age 2 and be sure to choose Oceanus which will allow you to create Caladria at the temple.
2. Build all houses to allow for max troops/units and make any upgrades at the temple for this troop type.
3. Build Caladria via temple and then send them to the enemy base, from here let them hover above the enemy and as they get attacked they will self heal. Do this until the achievement pops.

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