Hi achievement hunters!
Very simple and easy achievement, just wanted to make a bit more clear.
After 1 or 2 horde matches you will unlock a special melee ability, the first one to unlock is the “Blade” as soon as you next start a game with it equipped it will build up (around 30 second timer) you then get close to a zombie once it’s ready and press the right analogue stick in and you will slash the zombie with the special blade and boom! Achievement unlocked 👍