Similar to Stairhopping this technique consist on stacking three objects by a ledge so you can walk from your current floor to a lower or higher floor (there's no two second delay because of walking to the new floor). This is one way to kill creatures while receiving none or low damage. Other ways are shoothing a monster through a window or closing and opening a door.
This is often used in spawns like Behemoths in Cyclopolis or the single Giant Spider in Darashia. Also often used by low levels that can't handle a creature that would most likely give them equipment (Ghouls for example).