Build a mob arena

1. Start the game

Add a wave objective on the sidebar, reset it, and kick off the first wave. * targets every player tracked by the scoreboard.

# functions/arena/start.mcfunction
scoreboard objectives add wave dummy "Wave"
scoreboard objectives setdisplay sidebar wave
scoreboard players set * wave 0
function arena/next_wave

2. Spawn a wave

Bump the wave counter, announce it, and summon the mobs. Every mob gets the foe tag — that tag is how we'll tell "our" arena mobs apart from anything else in the world. The last argument on /summon is a spawn event; here it also names them with the tag.

# functions/arena/next_wave.mcfunction
scoreboard players add * wave 1
title @a title New wave!
summon zombie ~ ~ ~5 minecraft:spawn_zombie foe
summon zombie ~5 ~ ~ minecraft:spawn_zombie foe
summon zombie ~-5 ~ ~ minecraft:spawn_zombie foe

Simplest version: give the tag by running tag @e[type=zombie,r=10] add foe right after the summons if your version doesn't tag on spawn.

3. Detect a cleared wave

This is the whole engine: each tick, if there are no entities tagged foe left, run the next wave. Kill them all and the arena reloads automatically.

# functions/tick.mcfunction (via tick.json)
execute unless entity @e[tag=foe] run function arena/next_wave

execute unless entity @e[tag=foe] is the key line — "unless any foe exists."

Make it harder each wave

• · Spawn more mobs on higher waves: execute if score @a wave matches 5.. before extra summons.
• · Mix in skeletons and spiders once players get comfortable.
• · Reward survivors with /give or /effect between waves.
• · End the run at a boss wave — summon a single ravager tagged foe and show a win title when it dies.

See it in Minecraft

Run a wave and the arena fills — a "New wave!" banner drops and the tagged mobs spawn in around the players.

The dungeon arena in the shot is a few fills — run this once, then let the waves spawn:

# functions/arena/build.mcfunction
fill ~-12 ~-1 ~-12 ~12 ~-1 ~12 stone_bricks
fill ~-12 ~ ~-12 ~12 ~5 ~12 stone_bricks hollow
fill ~-11 ~5 ~-11 ~11 ~5 ~11 sea_lantern