Blacksad
Explorer
Zelda Themelin said:
Well, this might be mistake in my part. Oh, it would be great to find out it has been all this time.
So tell me that Sigil is not in center of Concordant Oppision (where neither nor god can come closer than 100 miles of center). Sigil seems to be set over the center.
At the center no gods and spells can function, but it has been mentioned that due to its position (at the top of the spire, if the effect are sphere and not cylinder, it would explain why it isn't affected by restriction on spell, other unknow properties of the plane is still a possibilty), or its nature (it has been mentioned that Sigil might be a demi-plane, that would be why it alter so wildly the rule of the plane it is attached to) spell can still be cast, cleric still receive spells, but no planar travel magic works.
The designer of the setting let many things at the DM's decision, Sigil mysteries is like the Dark Powers for Ravenloft, it has been decided to never print the "truth" or "canon" on it to allow DM to customize their campaign, it's probably the same thing for Sigil, while they still mention some possible reasons.