Dreams are definitely a good way to go. You can really setup some bizarre scenarios. And there is always the dream/vision of their own death (much better if setup a long time before it happens).
Graphic detail of most dungeon experiences is enough to frighten anyone.
Rot grubs!
Random d20 rolls for no reason - regardless of the result cringe and fumble around behind your DM screen a bit.
Any kind of nasty egg or pupa that starts to hatch - best used in dim light so they don't see there are bunches surrounding them until they set ablaze the one they can see.
Attacks from all directions: each side, above and below... heck throw in ethereal attackers as well.
During a particularly nasty encounter at night or in a dungeon (hags are always good for this), trip the lights in the room you're playing in and let out a high pitch scream. Best to secure beverages and the like first however.
Screw with the players: Warrior charges the BB and draws a weapon only to realize its not there. Spells fizzle or have an entirely different effect. A party member disappears.
While on watch, the night suddenly goes dead silent. The watchman, looking around, sees a shadowy cloaked figure on top of a sleeping party member. It appears to be "sucking" energy from the character. It looks at the watchman, roll a save vs. Paralysis!
Graphic detail of most dungeon experiences is enough to frighten anyone.
Rot grubs!
Random d20 rolls for no reason - regardless of the result cringe and fumble around behind your DM screen a bit.
Any kind of nasty egg or pupa that starts to hatch - best used in dim light so they don't see there are bunches surrounding them until they set ablaze the one they can see.
Attacks from all directions: each side, above and below... heck throw in ethereal attackers as well.
During a particularly nasty encounter at night or in a dungeon (hags are always good for this), trip the lights in the room you're playing in and let out a high pitch scream. Best to secure beverages and the like first however.
Screw with the players: Warrior charges the BB and draws a weapon only to realize its not there. Spells fizzle or have an entirely different effect. A party member disappears.
While on watch, the night suddenly goes dead silent. The watchman, looking around, sees a shadowy cloaked figure on top of a sleeping party member. It appears to be "sucking" energy from the character. It looks at the watchman, roll a save vs. Paralysis!