Minecraft wiki entry for Building_a_rollercoaster, associated text: Kill: /execute @e[type=player] ~ ~ ~ /kill @e[TARGETOR]
Teleport: /execute @e[type=player] ~ ~ ~ /tp @e[TARGETOR] DESTINATION
Freeze: /execute @e[type=player] ~ ~ ~ /execute @e[TARGETOR] ~ ~ ~ /tp @s @s