Every day at 00:00 UTC the challenge rotates to a different weapon and a kill target. Clear it and your streak survives another day.
Streaks earn five trophies — at 7 days, 30 days, 90 days, 180 days and a full year. They are awarded from your longest streak ever, so a trophy is never taken back, and the year trophy puts a badge beside your name on your public profile. Start a streak today.