Undead Stalking the Graveyard

I created a graveyard to scare PCs. It scared them because their enemies were unknown and could ambush them at any moment.

I'm participating in the October RPG Blog Carnival and its theme is horror.

I once had a party with a paladin and a cleric that were happy when they encountered undead.
These characters were extremely effective against undead.
So I created a cemetery with a huge underground labyrinth, crawling with undead.


The undead feared sunlight and didn't come out during the day, they also couldn't leave the graveyard.
In the labyrinth was a permanent darkness effect which limited how far PCs could see,
even with magical light.

So during the day, everything looks ok, by night the graveyard is crawling with zombies, ghouls, etc.
When the PCs went down into the labyrinth they couldn't see much before or behind them.
Ghouls crawled their way through the walls and followed the PCs from a distance.
The PCs noticed this and turned back, only to have the ghouls crawl back through the walls.

This scared the PCs and players and they decided to leave the graveyard alone.

This setup worked because:

• I limited the PCs vision and knowledge of their surroundings.

• The PCs didn't know how strong the undead were or how many there were.
  The undead also avoided combat, thus limiting the knowledge the PCs have of them.

• The idea that they could be ambushed at any time was unsettling.