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 do it three times, to add three seperate players to the game. if done right you'll have a full screen with four players on it!)
Before starting the round, make sure you vote for the Snowball version of Tumble in the vote menu. Alternatively, when you're creating the round, go into the Settings and set the game type to Snowball only.
Once in the round, make sure you've switched to the account you want the trophy on. Then, it's as simple as throwing snowballs at each of the other "fake" players until they fall into lava. Make sure you don't simply destroy the blocks at their feet, but actually physically knock them into lava using the snowballs. Once the other three players are defeated, the trophy should pop.