SMITE

As Cliodhna, damage an enemy god within 3s of leaving a wall 10 times in a single match.

Cliodhna has a passive that allows you to enter all walls on a map, simply by walking towards it. While inside the wall, you slowly take an increasing amount of tick damage, so you can't stay in there for long. Once you exit the wall, you'll have to wait 16 more seconds before you can enter a wall again, and you cannot enter a wall if you have less than 25% health.

For this achievement, you need to damage enemy gods 10 times in a single match when leaving a wall. There are two ways to do this. The first and best way is to use Cliodhna's 3, Lurching Claw, which will make you dash forwards. You'll do damage to any enemy you pass through and then you can cancel the ability early (or at max range), after which you'll slash any enemy in a small cone in front of you.

This is most likely best attempted in Joust or Conquest (Clash or Siege would work too), purely due to there being more walls available for you to enter and pounce from. It will be possible in Arena, however you have far fewer walls to play with. Other than this advice, I'd recommend building some cooldown to help with how often you can use your abilities (although with the passive cooldown, this may not make much difference).

You can also build a bit more hybrid, with power and defences, to allow you to last a little longer in the wall and still be able to get kills. Remember though, this is purely for achievements and isn't necessarily the best build for her in regular jungle play.

Really, you should get this quite easily over time during natural play in one normal conquest game.