When the developers added Uber 10 into the game they added bomber royale as a means of getting this. To get this in bomber royale you need to get 500 total kills. This should take about 20 hours more or less so you should probably save this achievement for last. If you're having trouble finding people you may have to wait for saturday (xp day) to play. TRACKEY has commented on the older solution to type "/stats" into the game chat to check how many bomber royale kills you have.
If you're new to the mode or having trouble here is a link to the basics https://trove.fandom.com/wiki/Bomber_Royale
. I would especially pay close attention to where it talks about powerups. Knowing about how they work and what they do will make you a better player. The more powerups you pick up the better. The rubber bomb is your main source of damage so the rubber bomb powerups should almost always be your #1 priority. When you're using your rubber bomb don't throw it directly at people. You could throw it at the ground and have it bounce to where a person is heading or throw it at a wall and have it ricochet towards them. You could also use the blocks of the world to your advantage. Anywhere you see a 90 degree angle where two blocks are touching you can throw your bomb in that corner to make it blow up much quicker. The climbing claw is only used for staying alive or getting somewhere else quickly. You should always have a health powerup on you; you can only carry 1 so if you're next to another just use the one you have and pick up the new one so nobody else gets it. The lava bomb isnt great for killing and is mostly just used for limiting people's options. The sticky bomb's explosion goes through blocks so its smart to hide the location of where it's thrown rather then just throwing it out in the open. If you're chasing someone down it can be a good idea to throw a sticky bomb ahead of them, limiting their options and then spamming your rubber bomb in the new direction they go towards. When someone is chasing you don't go in a predictable direction. I would only use the bomb jump as a means of damage to another player if you think they're under 5000 health. I suggest that you learn the layout of the maps and where the powerups spawn so at the start of the game you have a route in mind you can use to grab powerups before other players get to them.
Being in enclosed spaces can be dangerous but will net you a lot of kills if you know what you're doing and are better then the person you're fighting. Some maps have waterfalls you can use to save yourself if you fall off the map, just go in the middle of the waterfall block and spam a to go up. I'm not sure if this has been patched yet but sometimes there's a glitch that happens that creates a infinite source of water you can abuse and stay in til someone kills you, which is not easy. Don't be that guy that abuses it, chances are you probably won't be getting many kills in it anyways. Remember you're here to get 500 kills in this mode, don't hide or wait for people to come to you.