It's quite simple.
When player falls down event is triggered and strategy chain is executed.
default action is no action, he will die.

This is now implemented as "onFallThroughWorld", as in:

events:
  onFallThroughWorld:
    - homeMultiWorld

If defined and a location is returned from the strategy chain, the player will be teleported safely to the destination rather than killed.

Thanks a lot!