Frist make a small room players cannot get out of with a spawn pad.
Then put down a weapon (it can be any weapon).
Then place a button inside the room and in “Button message” type "Enter arena.
Then place a teleporter outside of the room.
Wire the button to the teleporter and make sure the in and out are like this,
“Button pressed–Teleport player here.”
Place down a property device and set the “property name” to “Players.”
set the “property type” to “number” and “default value” to “0.”
Place a lifecycle device down, and set the “event” to “Player knocked out.”
Place a text down and make it not visible in the game.
Wire the Teleporter to the text and make it like this,
“Teleport player here–Run wire pulse block.”
Then go to blocks make a new one and enter the block code.