Realm Royale Reforged

This game has 4 classes. The Assassin is the third on the list, For this you have to simply eliminate another player as this class.

Elimination comes in two stages, first is to do enough damage to turn them into a chicken, then you need to kill the chicken before it turns back into the human form again.

Once you kill the chicken form, you will pop this acheivement as soon as you score the kill.

This isn't a full guide but a fairly easy way of getting this achievement with minimal skill/effort and just a tiny bit of luck was to load into games, wait for them to start, and just stay inside of the airship to the very last second and not adjust where you will land. More times than not, at least one player will do the exact same but because they are afk. So you are able to just kill them with your knife since they won't really be fighting back. This will also often give you potions and resources to be able to use for crafting at the forge. Must be done as the Assassin