Hi, main main specialization as a freelancer is minecraft modding, i have created many plugins and mods for every possible solution (bukkit,spigot,paper,forge,fabric,sponge). You can chceck my reviews on my profile form past minecraft modding jobs. I will be happy to make duels plugin for you, but there is one catch, overall plugin might be more costly than 250usd because to meet all your reqieremnts it will take many working hours i estimate about 50-75 hours of programing and testing. If you decide to hire me for this project my hourly rate is 10usd/hour. also all bug fixes are free for this version of game even after project is complited. If you have any further questions feel free to dm me.