thanks for the reply 
that would work but no matter what, you would walk into it eventually from the platforms, the best way to describe it is a huge vertical pipe with ledges inside of it spiralling from top to bottom for the player to jump onto… you have to get to the bottom of the pipe via the ledges/platforms, but if you jump straight down i want to kill player… unless I do the sized kill z and have it turn off on the last ledge if that can be done ?