* BrokenBase:
** The Xaositects faction earns a lot of flak because their faction write up actually holds up ChaoticStupid as ''an ideal to live up to''. Needless to say, many DMs ban party members from belonging to this faction.
** The Blood War is regarded by many fans as being an incredible, epic piece of background lore and iconic to the setting... and a significant number instead hate it, generally citing either its PlotTumor nature or the UnfortunateImplications about the impotence of the forces of Good that it reveals. 4th edition ''TabletopGames/DungeonsAndDragons'' actually got rid of the Blood War as it used to be, ''because'' the designers felt it was overdone, over-hyped, and tended to overshadow everything else about Sigil and the planes.
** The Faction War is a deeply controversial aspect of the setting, resulting in deep divides between those who loved the original factions and those who loved the new ones.
* CrazyAwesome: The Xaositects' speciality. They live in frequent flash-mobs where any number of them from one to "everyone able" may go hurl wild magic at Hardhead patrols or make a great art piece just because one of them felt like it at the moment and others thought it was a great idea. The Revolutionary League infiltrates other factions with a subversive intent? A Xaositect infiltrated ''them'' for years -- just for lulz.
* MagnificentBastard: Duke Rowan Darkwood, the factol of the Fated, instigated the Faction War and afterward became one of the few people to ever escape from the Lady of Pain's mazes ([[Videogame/PlanescapeTorment The Nameless One and Ravel Puzzlewell]] being two others).
** Although she ''definitely'' got the last laugh.
* NightmareFuel: All of the Lower Planes. NightmareFuel can appear in other places throughout the setting as well.
* MoralEventHorizon: Rowan Darkwood. His plans to instigate the Faction War involved taking control over the Mercykillers. He couldn't do that without seducing Alishon Nilesia, who while being a KnightTemplar, was a 19-years old girl. After winning her heart, he persuaded her to marry him and involve him in her faction's chain of command. Then he sold her into slavery to the fiends.
* ParanoiaFuel: Portals. They can be anywhere. Any opening can be a portal, from a door to a rat hole to the opening in a barrel to an arch over a street. Its impossible to be certain where one may pop up until someone stumbles by with that portal's key, which can be anything from a priceless artifact to a stray thought or memory. And they can lead anywhere, from Mount Celestia to Toril to any of the Nine Hells. It's an accepted risk to living in Sigil that one can trip right into a portal without knowing it and end up on another plane altogether. Just walking into your front house can lead you to the Ash Wastes.