Collapse

Picture of a structure collapsing In motion

A structure collapses if no connection to a stable block is existent. Everything that is not connected will fall down and damage blocks that get hit. Different blocks have different "weight" and normally fall down in a straight line (with slight variation)

Stone blocks will destroy most other blocks (except stone and teamdoors) immediately on impact, players getting hit by falling stone blocks instantly die aswell.

"Lightweight" blocks like ladders, teambridges and stone walls will have less devastating effects. They won't kill players or damage most other blocks. Ladders normally get destroyed by any other block falling on them.