Quote Originally Posted by ShurikVch View Post
Source?
At the end of Die, Vecna Die! she restructured the entire order of the multiverse as the official canon reason for the tradition to 3e rules from 2e. If she has the power to change the underlying mechanics of the universe, across all the Inner and Outer planes, I'm pretty sure she's able to smite a worshipper outside of Sigil.

Oh, and there was that time when she just straight-up murdered Aoskar despite (like every other deity) Aoskar being unable to enter the Cage.

If she can kill a god on his home plane without warning or notice, odds are she can do the same for mortals trying to worship her outside Sigil.