Dead Island: Riptide Definitive Edition

Whilst playing with randoms or joining a buddy's game. When looking at any enemy. Press whilst looking at a hostile and have your buddy kill the enemy you tagged. The marker lasts about 10 seconds before disappearing.

You can only mark one enemy at a time per person so I would probably recommend running around the Pinai Ferry Station since there's about 20+ enemies.

You can either jump on top of the car at the end of the pier by the Twin Kayden (has all the bags on top) or set up perch on top of the billboard with the truck and sniper rifle. Fast Travel to Henderson and then back after the enemy respawns start thinning out.
Should take about 15 minutes per person give or take