Crowded Colosseum

Steps

1. Wait for the crowd to gatherStay on the Colosseum until the timer runs out.
2. Shoot the grey target on the south pillarIt blends into the wall, on a pillar near the arena gate. Only a gun sets it off.
3. Hit 18 targets in 90 secondsFollow the arrow. The next target pops up nearby. Any weapon works.