Blade trap

Version 0.11: This article may not be up to date for the latest stable release of Crawl.

You can see the edge of a massive scythe-like blade hidden in a slit; it probably has a counterweight that acts as a pendulum.

A blade trap is a trap which, when stepped on, causes a huge blade to swing down and slice the player, causing huge damage if it hits. It is the most powerful of all the mechanical traps, doing between dungeon level*2 and (dungeon level*2)+29 base damage to the player, and between 10 and 38 base damage to monsters.