Armlet of Mordiggian

The Armlet of Mordiggian is an item purchasable at the Main Shop, under Weapons.

Additional Information
Currently in DotA 2 heroes can buy multiple Armlets, but the active effect does not stack.

Armlet toggling
By turning on the armlet you will gradually gain 475 hp due to the strength it gives you. You lose the health again when you deactivate it, but you cannot go below 1 hp. This can be used to your advantage. If you are below 475 hp, you will lose all but 1 health. When you activate it again (quickly, so the enemy won't have time to kill you when you're at 1 hp) you will end up with 475 hp, more than what you had before. This can make you survive much longer.

Trivia

 * Armlet of Mordiggian is named after Mordiggian, a deity in the Cthulhu Mythos created by Clark Ashton Smith in his story The Charnel God (1934), whose powers consist of sucking away life force and whose cult consists entirely of ghouls.
 * Lone Druid's Spirit Bear is normally affected by the HP drain, and does not benefit from the strength bonus.