Set Up a Totem Trap for Multiple Players
Prepare Your Totem
Obtain a Totem of Null by running /givet 1 in chat. Make sure it's in your main hand—the totem only works when held there.
Tag Your Targets
With the totem in hand, type /ttag <player> for each player you want to trap. You can tag as many players as you want onto a single totem. Double-check each name is spelled correctly, as the command won't warn you if a player doesn't exist.
Activate the Trap
Once all your targets are tagged, take fatal damage while holding the totem. This can be fall damage, fire, suffocation, or any other damage source. When the totem breaks, all tagged players will instantly be sent into the void, regardless of where they are on the map.
Important Notes
Duplicated totems from creative mode or item duplication exploits will not function. Only legitimately obtained totems work. If you need to remove a tag before activation, use /tuntag <player> while holding the totem.