Trap theory & easy trap ideas

 I don't like pitfalls as a trap. You're walking along and fwummpp 2d6 damage ya goof. I prefer the psychological thing where the players go "uhh this thing looks like it might kill us? should we even fuck with it or just go around? who's got the big stick?" I want them to say the same thing about monsters too. Monsters are traps that chase you down the hallway.

That being said sometimes you just gotta put dangerous stuff laying around for the players to blunder into. The dungeon doesn't like you. You are its food. It doesn't exist for the players to loot. It exists to lure assholes to their deaths and harvest their intestines as food for asexual reproduction like an amoeba. 

"you have to step on this thing" traps don't make sense unless the players actually step on it. Then you gotta give em a reason to say they step on it. Like the rug in front of a nice armoire, in the process of opening the armoire you'll step on the rug. I guess this is why the old books say pressure plate traps only go off on 1-in-6, that's the odds you'll step just on the right spot.

we have tasty nectar for you

Traps can look like a fun thing to play with but there should be a hint that something is wrong. Just a hint. The natural world is full of traps and ambush predators. They do their job by trying to look harmless or having a seductive thing to lure unwary victims.

If you think of the dungeon as a living entity that wants to eat the players, but be really lazy about it, you're on your way to thinking up a good trap.

rusted chains iron jaw

How to make a trap
When my brain isn't working and I can't think of  clever trap a lot of times I just take an item or feature that might legitimately exist in the dungeon and make it ugly and dangerous. Maybe put a piece of bait near it (or the barely recognizable remains of a corpse). It's easy to think of an effect when you know what the thing is supposed to be for. If you do this long enough weird shit starts coming out.

The fun is letting the players interact with it up to the point where they go "maybe this is a bad idea"

Some of these aren't really traps.

D46 trapped cursed dangerous tricks

1. Suit of rusty armor with demons carved on it. When you put it on it locks up and needles tipped with poison pierce the wearer.
2. Braizer full of coals. Stinks like death. Billows toxic fumes if lit.
3. A mirror. If you get too close to it your reflection tries to grab you and pull you in.
4. A sign "dont go in the hallway". You can see treasure at the end of the hallway. Really it's a teleportation trap, or just before you get to the end of the hall right at the last second it releases a flood of lava.
5. Cauldron with a curious ladder going in. Lid slams shut, fills with boiling water.
6. Tall unstable looking pillars delicately balancing on jade frog statues with gems embedded in them.
7. Vase of flowers that releases sleeping gas
8. Suspended animation tubes containing rare animals floating in horrific stone/metal melting acid.
9. wand of self-detonation?
10. A huge brass bowl with treasure in the bottom and a ladder going up. Pissy fire elemental underneath.
11. A river full of piranhas
12. A big statue that follows the players just out of sight. Blocks up the passage when they try to flee from another enemy
13. Black and white tiled floor. Step on the black tiles and they get super hot.
14. a giant hand hanging in the middle of the room. At first it just looks like a grotesque chandelier. Swoops down and grabs you as you pass underneath. Lifts/drops or crushes or something worse.
15. A freshly dug grave with a pale swollen body in it. If you climb in to investigate the body it comes to life or an unseen servant dumps soil on you.
16. a staircase that seems like its going up, but really it's going down, or going to a completely different place, or only goes one way.
17. a mask that changes your face when you take it off.
18. water or food. It's poison.
19. A book that take memories out of your head or eats your spells.
20. A knife that only heals people you hate with its stabs.
21. A bow powered by fingers.
22. pants that make you impotent
23. flowers in a nice vase laced with bones-to-rubber pollen
24. a friendly campfire that feels warm but causes hypothermia
25. bowl or fork that rots food it touches
26. a drawer with an imp in it, the drawer is rattling. the imp craves your friendship and affection like a pitiful ex but horrifically fucks up everything it tries to do and misunderstands every instruction. also its indestructible. an anti-familiar. An unfamiliar?
27. a small walkway across a yawning chasm. halfway across a bucket of oil falls on you and goblins start shooting flaming arrows.
28. it looks like an elevator, but it's really an incenerator.
29. a potion containing a mean ghost, a tornado, or an ocean.
30. the foot of a little girl. if you touch it with your bare skin she starts following you around pushing buttons.
31. a window that looks like it goes outside from deep in the dungeon. if you open it all the air gets sucked out of the room.
32. a river that rusts metal
33. a skull that feeds on magic
34. an expensive rare gem encrusted thing that carries an anti-magic field
35. a drinking horn that bites your lips off.
36. nice looking shoes. under the insert is a portal to rusty nail world.
37. bandages of +1 septic infection
38. a really long hallway lined with drills
39. a slippery chute off a cliff. you manage to survive the fall but now the tide is moving in and there's something in the water
40.  a portrait that changes to show the last person that looked at it
41. a valuable looking crystal protrusion covered in microhairs that pierce your hand and burrow into your heart
42. a door that swings itself open wildly and knocks your ass off a ledge
43. stuff that hisses faintly. explodes if you pick it up.
44. a hallway covered in acid pustules. there's an imp with a fork jumping around it like a bouncehouse
45. a little hole with a nice cute friendly mouse in it that walks with a cane. the mouse is a compulsive liar and friends with a bugbear.
46. an expensive rug covering a hole in the floor. under the hole is a gleeful giant with its lips pressed up against the hole. or maybe his lips are pressed thru the hole and they look like comfy cushions to sit on