insta-death_trap

An insta-death trap is basically a trap which activates and ignores HP/defensive qualities of a character, instantly killing him. Used for area denial and offensive architecture, creating a level of danger that cannot be bypassed with stats.
Using this design for mundane random objects such as trapped chests is discouraged, usually such traps are part of permanent terrain/buildings feature that force players to research safe paths and remember the layout of buildings.