Instadeath

An instadeath, short for instant death, is a mechanism which, when applied, guarantees that you die immediately, even if you had hundreds of HP. If you have a wand of death or finger of death, then you can instadeath some monsters.

Causes of instadeaths are:
 * Cockatrices
 * Touching a cockatrice or chickatrice corpse without gloves.
 * Eating a cockatrice or chickatrice corpse, or eating the corpse of Medusa
 * Kicking a cockatrice or chickatrice corpse without shoes.
 * Being hit by a death ray while not having magic resistance. This can be achieved by:
 * zapping yourself with a wand of death or a finger of death. ("You irradiate yourself with pure energy!")
 * zapping a wand of death or finger of death at a monster, and being hit by the ray reflecting off a wall, or the monster's reflection.
 * having a monster with a wand of death zap you, typically the Gnome With The Wand Of Death.
 * being touched by the touch of death. The Wizard of Yendor and high level liches can use this against you.
 * Occasionally, poison (especially food poisoning) causes an instadeath, unless you have poison resistance.
 * Standing near a collapsing drawbridge.
 * Being drowned by a sea monster, although this technically takes at least 2 turns.
 * Intentionally level teleport yourself to level 0 or any "higher" level - level 0 is nowhere, -1 to -8 is "above the clouds", -9 is Cloud Nine and -10 and above is Heaven.
 * Suffering a system shock while attempting a self-polymorph. Technically, you only lose up to 30 hit points, but this is often fatal to low level characters.