What does it do?

!Dying

Whenever you die, it will place a revivestone for you. (Highly recommend corpse for keeping your items)

What does the revivestone do?

!Reviving

When another player happens to stumble on it, they may right click it to save you after a while. You will get weak after being reborn, and your reviver will lose some hunger.

How hard is it to find the revivestone?

!Block seen through walls

When you die, it will broadcast your death coordinates to your location, (and you may type /h.xaerosupp to have it broadcast a waypoint for xaero's minimap as well) and will have a glowing effect through walls.