I found this tonight on our Xbox realm and made sure it was repeatable. By placing a campfire below some hostile mobs and hitting them with your fire aspect 2 sword, you end up lighting the campfire and can easily kill the rest of the mobs quickly. In the clip the zombies have already fallen so they are at a 1-hit kill but I feel like the campfire shouldn't light up this way.

Edit: ignore what is written above, found out this is actually a feature on wiki page but I dont know how to delete report