Use a zone, a trigger loop, and damagers.
A trigger loop is two triggers connected in an infinite loop with wires (make sure to add a trigger delay of however long you want)
Player enters zone → Trigger (Start the trigger loop) : Every time a Trigger is triggered have it transmit on a channel called “damage”, the damager device should receive on the channel “damage”.
When the players leaves the zone, stop the triggers.
Well if he doesn’t want the damage to stop when the player leaves the frozen wasteland, then he doesn’t have to do this part: