D&D 3.0: Tales from Mystara
The Hearthstone is a magical, heartshaped stone that gives off a bright red light. It’s a diminutive red crystal of about three pounds in weight. The magical powers of the stone are undefined but it theorized by scholars that it has to be related to alignment. Effects like Know Alignment, Change Alignment or Confuse Alignment are expected.
Kenalas Silverstreak explains:
" I have just received this small black box from Karamekos via teleport. There are some instructions attached.
1. Do not touch the Hearthstone. If Hearthstone is outside its container, deposit in the container and close immediately.
2. Exposure to the Hearthstone is dangerous. Place inside container without touching in 12 seconds or less.
3. The box and the inscription on its back is needed to destroy the item. With the stone inside the box, throw box in a big source of fire (10d6 or more) and recite inscription aloud twice.
Inscription: “Animulus exedo corporis, flamma exedo animulus.”