Immortals Fenyx Rising

The Abas are the lizard-like creatures that burrow into the ground Bugs Bunny style. You first encounter them while helping Demeter pretty early on in the story, but to get them out of the ground, you'll need the Slam ability. You get this shortly after finishing Demeter's Sanctuary. When she has you slam the Abas out of their nests in the ground, then you can begin working on this. Killing Abas while they're underground will NOT count (they must survive the slam), so you can do this in one of two ways:

1. If you are on easier difficulties, you want to try and do this against the Abas who have golden framed health bars. They're the only ones who can survive your slam on easy. You'll be able to do one slam per Elite Abas. There's plenty throughout the game and they spawn in all regions after you first encounter them.

2. If you want this right away, you can temporarily raise your difficulty to hard, and just run around a group of enemies with some Abas and wait until they burrow, and with the Elites you can get about 4 or 5 slams on one Abas. With this method you can theoretically get it in one fight, but that's only if you really want it over with.

Note: If your achievement gets bugged or doesn't track properly, here is the workaround from the comments, courtesy of ruyas:
So after starting a new game and getting back to that point I was able to get the achievement without any issues. Same goes for the ash leech achievement

During the quest, Gardenien of the Gaurden Wait What?, you will talk to Demeter and unlock the Catastrophe Quake ability. Then you'll be told to use it to defeat some nearby Abas. You can grind it out right here, by using the ability to knock them out of the ground and instead of attacking them, create some separation so they go back under ground. Rinse and repeat. If you have already made it past this area, don't worry there are plenty more Abas that you can grind this on all across the map.