Trebor's ghost haunts the dungeon, and will seek you out. If ever you meet him, he will instantly slay you. Eventually, you can dispel the curse you put on him and so end the trouble, but that will be a long time in coming. You will hear him as you both wander the level. There are several things you can hear, which indicate how close he is. If he starts to get close, run for safety on another part of the level (being a ghost, he can pass through walls and over obstacles), or save and reload. In the original version, the ghost moves in real time (yes, the original Wizardry IV was not purely turn-based), so in the main dungeon view you can't be slow about moving around (the ghost does not move when you are in combat, at a pentagram or other event square, or encamped). In the Archives version, he does not move unless you press keys while in the main dungeon view (this includes keys that do not normally do anything).