It could be a Spleef arena at the server

if you dont know what is its a plain arena and the 2 players should get a diamond Shovel and the ground

shoud be made of dirt (or wool) the enemy must make the othe player fell at the water and be sure they

cant get up again

Sorry For Bad English

Edit:they dont need to keep the shovel forever and they dont need to be stuck forever just Tp or make the water a portal