I'd recommend doing the "fake" multiplayer glitch for this trophy, which you can find how to do here: https://pastebin.com/Jgf6vPeJ
(keep in mind you'll need to repeat this glitch again to add a third player)
In a public round of Battle, try and find yourself a bow and arrow, as well as any sort of weapon. Once you have these, run up to the second account you added to the round. Hit them with your weapon until they're close to dying, and then shoot them with your bow. Repeat this for the third account you added to the game, and once they're both dead, the trophy will pop.