Age of Mythology: Retold

Easiest way to do is by using the editor. Classic age trick.
Open the editor by pressing menu button in top-right corner, go to object -> create object, pick units in drop down menu and create militias for player 1 and enemy villagers for player 2. You can copy-paste to do it faster (icons under triggers)
I also made player 1 poseidon, but don't think it matters.
Save the scenario.
Start skirmish, choose "custom scenario" and choose the one you created, start the game. If you created more than 50 villagers you will get it in less than a minute.

Easiest way to do this is during scenario 7 of the Trident campaign, called "More Bandits". Early in the scenario you will free some Centaurs. Directly northeast of you is another area with green militia being hunted and more soldiers captured. Use the Peace power and march there. That way you can keep most, maybe even all, Militia alive. Defeat all the enemies there and put Arkantos in a group with the militia. Put Arkantos on passive. Then break the gate southeast.
Here make a save. We can load it after killing until we run out of militia and it still counts.
Then, just with Arkantos and your militia (I had a good dozen) go down and start killing the enemies. Manually use Arkantos' skill by pressing Q whenever available. That will increase the power of the militia enough for you to kill most, possibly all the enemies here. You should also rescue some more militia doing that.
Overall I made roughly half the necessary kills in one run this way and only had to load my save once.