Wargears are a fun minigame, they are builds designed to destroy eachother with tnt cannons (usually dispensers are banned). you can make your own rules but i suggest looking into the steamwar.de ruleset of MiniWargear because its the easiest to build/play with. (it is in german but you can use a translater)
people can choose between public and private wargears. public ones have been made by others and chosen to be public. private wargears you make yourself and can design it the way you like so long as you follow the rules. in a battle a 30 second countdown starts after both teams have clicked ready. after this 30 second countdown you can place blocks and tnt damage is enabled.
i would love to see this on CubedCraft but understand the complexity of adding a whole new system.