6 Votes


Hits: 1666
Comments: 12
Ideas: 0
Rating: 3.4167
Condition: Normal
ID: 6129


September 14, 2010, 11:18 am

Vote Hall of Honour

You must be a member to use HoH votes.
Author Status


Recursive Portal Trap


Now you're DMing with Portals!


"You enter the hallway. About thirty feet away behind a pit, a goblin jeers at you, pulling out a bow."

"I shoot my longbow at the goblin."

"Your arrow flies towards the goblin, but disappears before it hits."

"I shoot again."

"Your arrow disappears as before. From behind you, an arrow strikes you in the back."

"I try and see where the arrow came from."

"It's one of yours."


The dual portal trap is set up as follows:


Portal (1), open space (O), second portal(2), pit or other hindering terrain a monster can hide on the other side of (X), and then a hostile monster with a ranged attack (M)

Ranged attacks entering either portal disappear, coming out of the opposite portal the next round. Portals release projectiles towards the opposite portal, meaning that ranged attacks can indefinitely move between the portals. The magic of the portals actively aim projectiles at any creatures in the area between the portals. The portals only affect ranged projectiles and magic, and creatures pass through them with no effect. If a monster tries to attack the party from the far end of the trap, their projectiles are caught by the portal, and then used to attack by the opposite portal. (For example, Monster M shoots at the blank space (O). His projectile disappears at portal 2, and then comes out of portal 1, aimed at any creature in the blank space, towards portal 2.)


The portals can be defeated through various methods:
Dispel spells, merely exiting the affected area of the trap, and bypassing it entirely. A group that makes no ranged attacks through the portals is in no danger from their own attacks.

Additional Ideas (0)

Please register to add an idea. It only takes a moment.

Join Now!!

Gain the ability to:
Vote and add your ideas to submissions.
Upvote and give XP to useful comments.
Work on submissions in private or flag them for assistance.
Earn XP and gain levels that give you more site abilities.
Join a Guild in the forums or complete a Quest and level-up your experience.
Comments ( 12 )
Commenters gain extra XP from Author votes.

Voted Pieh
September 14, 2010, 14:24
Short and sweet. Makes me want to map out an incredibly complex portal trap dungeon of some mad spacial warping abomination. Hm. Possibly some sort of giant flying lizard that craps alternating recursive portals everywhere.

Guide: "Don't step in that!"
Hero 1: "Ew, some sort of-" *Disappears*
Hero 2: "Where did he go?"
Guide: *Points up*
Hero 1: *Falling from a excrement portal on the ceiling"
September 14, 2010, 16:43
Another possibility is that the trap is already filled with projectiles loosed by previous victims of the trap- a whirling river of arrows, bolts and magic still hurtling down the passage.
September 17, 2010, 18:22
I don't know about this. Unless the portals add some sort of "push" to an object when it exits, most normal projectiles will eventually slow down and stop. Even magic projectiles might fissle out, given enough time, and some of those (ie fireballs) are probably subject to the same air friction as normal missiles anyway.

The "one over, one under" configuration would still work like this, though.
Voted Cheka Man
September 14, 2010, 19:05
A nice orginal little trap.
Voted EchoMirage
September 17, 2010, 7:08
Actually, two linked portals can be placed below each other. The lower one covers a shallow pit with something desirable. Once you go in, you fall - from the upper portal into the lower one, and again and again and again... until you are rescued, or die.
September 17, 2010, 9:06
Or you get pushed out of the effect through magic, psionics, ect.
September 17, 2010, 17:09
Don't forget - if you are pushed out later, not right away, you still will have quite a velocity, some 50m/s :D
Cheka Man
September 17, 2010, 18:51
If you fall for too long, not even grabbing onto a rope would help you, as your velocity would snap it.
September 24, 2010, 19:56
A levitate, fly or similar effect, magic or psionic, could get you out of the process of constant falling.

Plus, I'd see the dungeon "owner" needing to maintain the trap to keep it free of debris and mice and other stuff (read corpses). Alternatively, the magic of the portals could just teleport stuff somewhere else after some time of falling.
Voted herrozerro
November 2, 2010, 9:50

only voted

Voted Fishy2099
February 21, 2013, 12:57
A great idea
Voted valadaar
January 15, 2015, 15:23
Great stuff! Feels like it would be perfectly at home in Grimtooth's traps...


  • Associated ideas.
  • Trap

Random Idea Seed View All Idea Seeds

       By: MoonHunter

I was in a game with a GM that had a Masters in History, who made is a point to mention that the local peasants didn't have wheelbarrows. The rest of the players just shrugged that off but I knew that the GM was trying to tell us the peasants were on the knife edge of starvation.

All that from wheelbarrows? Yes, because before the invention of the wheelbarrow it took two men to carry that load. In it's time the wheelbarrow was the most explosive production multiplier that the peasantry could get their hands on.

This is worth two tips: One about the power of the Wheelbarrow and the other is the moral of the story...that people need to know the point you are trying to make.

Ideas  ( Society/ Organization ) | October 20, 2005 | View | UpVote 2xp

Creative Commons License
Individual submissions, unless otherwise noted by the author, are licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
and requires a link back to the original.

We would love it if you left a comment when you use an idea!
Powered by Lockmor 4.1 with Codeigniter | Copyright © 2013 Strolen's Citadel
A Role Player's Creative Workshop.
Read. Post. Play.
Optimized for anything except IE.