I'm running a Planescape game now and thought it might be nice to brain storm some strange and unusual encounters for the planes here. Since my players just got through an adventure on Avernus I'll start there.

Post 'em if you got 'em.

1) River of Blood - On Avernus a river of blood courses through the plane. It runs wide and deep in many places and fords are few and far between. A closer inspection of the river reveals the faces of tormented souls in the foam.

2) The Pillar of Skulls - Skulls is really a misnomer, the pillar is made up of disembodied heads. Live heads, live talking heads. A number of races are represented here, all of them talking and arguing amongst each other. The Pillar can be a source of information. If the characters can get it to coorporate with them.

3) "Flower" the Advanced Otyugh: Will trade the party coin for crap literally.

4) Court of Perfect Law, where the party is called to task for all the wrongs they have ever committed, whether a greater good resulted or not.

5) The Hag Market: Where anything - including the souls of the damned - is available for a price.

6) The Arena, where outsiders of all alignments are pitted against each other while beings across the multiverse watch via scrying. The bets are enormous, and the battles outlandish. How many lantern archons can one Balor defeat before going down?

7) The Howling Chasm

Between each of the lower planes is a series of deep and jagged chasms that all connect with each other.  Hidden in the crevices and caves you will find any creature that has ever escaped from the Lower Planes, for whatever reason.  Life expectancy for most normal folks here is very, very short.  It gets its name from the vicious winds that tear through there from time to time, and the howling some of the residents make due to insanity or what not.

The Bridge

A mass of flesh/bones/whatever that spans an otherwise dangerous/uncrossable chasm or river.  The Bridge demands a sacrifice of living sentient food before it will let the group cross.  If you fight it and might actually win, it simply retreats to the side they are not on and crawls down/up stream to somewhere else.  If they successfully kill it, it falls into the chasm or river leaving no way of crossing.

Nice GM's will have something other than a PC available on there side that can be fed to it.

9) The silver ship

This mysterious planeleaping vessel is staffed entirely by partially real illusions. It cruises through different planes seeking arcane knowledge of various sorts. For a fee or a task, the party can gain a berth about the ship, and perhaps discover some of its secrets.

10) The Inn at Worlds End.

This non-descript looking inn is located somewhere in the outlands far from any well travelled roads. It is when one enters the inn that its supernatural properties are discovered, for it is much larger on the inside than on the outside, and within one can meet all manner of sentient creatures from all over the multiverse. Ranging from gnomes to ancient and forgotten gods, at one table one can even find balors and solars sharing warstories and enjoying the finest rilmani wine. How this is possible is quite simple, for the owner of the inn is one of the oldest and perhaps the most powerful of all devils, who tired of the war between heaven and hell quit his position to take up barkeeping. The inn is protected by powerful enchantments, and any who would attempt to bring violence within its walls will quickly find that any damage they try to wreak upon others opens up wounds upon themselves. The rooms in the inn are not expensive, only 1 gp per person and night for a standard room.

Quote from: Krishnath10) The Inn at Worlds End.

This non-descript looking inn is located somewhere in the outlands far from any well travelled roads. It is when one enters the inn that its supernatural properties are discovered, for it is much larger on the inside than on the outside, and within one can meet all manner of sentient creatures from all over the multiverse. Ranging from gnomes to ancient and forgotten gods, at one table one can even find balors and solars sharing warstories and enjoying the finest rilmani wine. How this is possible is quite simple, for the owner of the inn is one of the oldest and perhaps the most powerful of all devils, who tired of the war between heaven and hell quit his position to take up barkeeping. The inn is protected by powerful enchantments, and any who would attempt to bring violence within its walls will quickly find that any damage they try to wreak upon others opens up wounds upon themselves. The rooms in the inn are not expensive, only 1 gp per person and night for a standard room.

THis has actally been done mutiple different times.  In almost every version of D&D.  In fact I think one version is actually named that.  Possibly from OD&D the Blackmoor modules.

Quote from: KnightcrawlerTHis has actally been done mutiple different times.  In almost every version of D&D.  In fact I think one version is actually named that.  Possibly from OD&D the Blackmoor modules.

Stole the idea from Neil Gaiman. :shrug:

11) The Island of the Mad Jester

Deep in the heart of Limbo is a floating island that is constantly chaging shape, and upon it lives the Mad Jester.  So insane, so unhinged from anything resembling normal, any who happen upon his island and cannot get away are subjected to his madness.  He is not evil, but he suffers from a pure form of insanity.  Some say the gods struck him as such, others say he is a god that lost his mind.  Even the residents of Limbo stay away from there, unless they are foolhardy, or insane themselves.

12) The Waystations

The Waystations are hidden caves, filled with ordinary supplies such as food, water, and basic equipment, scattered throughout the outer planes.  They are heavily protected against anyone who is not a mortal from the Material plane.  The Waystations were set up by an adventuring company called the Band of the Minotaur that had a very simple goal: to rob the outer planes blind.

The Waystations are most common in the lower planes for several reasons.  The upper planes tend to be more hospitable and easier to survive in.  The upper planes also tend to be better guarded, since the good residents care about each other's well being.  Most importantly, though, most of the best loot tends to be in the lower planes.

The Waystations are always well-hidden and the secret of them has only begun to leak out in adventuring circles.  While the Band has so far been tolerant of other groups using their stashes, it is likely that they would not be happy if they found a Waystation completely stripped of supplies.

Quote from: KnightcrawlerTHis has actally been done mutiple different times.  In almost every version of D&D.  In fact I think one version is actually named that.  Possibly from OD&D the Blackmoor modules.

It's called the Comeback Inn. It's found in the DA module series by Dave Arneson.