This challenge comes from the Dive! Mission of Fortnite Chapter 2 Season 1 during which you'll have to inflict a total of 200 damage points on descending supply drops. If you are wondering about it, supply drops are boxes with rare weapons and equipment that are dropped on the island at random locations. They are materialized on your mini-map by blue boxes.
The challenge is about bringing down these precious drops urgently, by shooting at them! Note that packages become "destructible" at very high altitudes.
During this weekly mission, many players are likely to shoot them down as soon as they appear. We recommend you to favor weapons with a good damage rate and a long range. Assault rifles are undoubtedly the best choice to quickly complete this challenge.
We recommend completing this challenge in Team Rumble mode, as it will help you avoid eager opponents early in the game.
