Overwatch 2

About the game mode
This achievement is exclusive to the Winter Wonderland event in december (every year). Might turn up in the Anniversary event (different random events every day in May). It can be found in the Arcade menu, it is the 8 player FFA mode not the 6v6.

Rules of snowball fight
Everyone plays Mei who has her wall and ice cube abilities from the main game. However she can only shoot icicles with a limited range and ammunition. One hit kills, the one who gets 15 kills first wins the game. Every player starts with 1 ammo and can get more by picking up (hold or ) piles of snow randomly appearing on the map (max 3). There is an important new ability by pressing the melee button : if someone shoots at you and you activate melee you can grab the icicle in the air and load it into your weapon. The ultimate attack is different as well: for a few seconds you can shoot as many icicles as you want with a greater speed. After the ultimate ends your weapon will be fully loaded with 3 ammo as well.

The achievement
You need your melee ability for this. Empty your gun before and walk in front of anyone who has ammo (their weapon glows red) and try to catch their icicle with . It is not that hard, the animation even lingers for a while. You can't spam melee but the cooldown is very short. One easy way to bait a shot is standing over a pile of snow with your empty weapon making the enemy think you are picking it up. After you caught it just kill the enemy with their own ammo. It supposed to work on any enemy but I can't confirm it. Best if you kill the owner of the icicle.