The form ability can be used to see someone one has met recently regardless of the physical distance. So far I understand it, but what is about another dimension thus in the shadow or underworld while you are in the material world?
Does it still work?
Also does it work if the other one is intangible and (normally) invisible to one?
To add to the other answer, there are three questions at the heart:
For a more Demon-sourced answer, let's look at the Process: Eliminator Cannon (Flowers of Hell, page 128.) It explicitly states "No physical range, but crossing into a different plane of existence (ie, Underworld) passes the Demon out of range."
According to CoD/WoD cosmology in general, different realms of existence cannot interact - the Demon and target must be in the same plane of reality.
This form ability allows a Demon to see a person in their location (or location.) So we have two stipulations:
When Doug tries to look at Nick, he can effortlessly see the empty park. If he wants to try and actually tell what Nick is wearing, that would then be trying to pierce the Obfsucate, and then the Clash of Wills**.
In that case, Clairvoyant Sight would turn up nothing, although potentially, a Clash of Wills. Personally though, Doug should prolly get suspicious if his favorite park is suddenly "gone."
Twilight is different because Twilight is not a separate plane, but a unique way to exist. Since Angels interact with Twilight a lot, it's worth breaking down as a special case.
The easiest way to describe Twilight is that it's a different physical "language." For example, Doug looks into a room where there are three horses and vier Pferde. He sees 3 animals, because he can't comprehend the others. Bound Barry (thanks to his Geist, Gary) can see all 7 animals.
Assuming Doug has no way to see into Twilight, if he tried to focus on someone in Twilight, he would again see the location with "no one" there.
** Clash of wills applies when two preternatural creatures attempt conflicting powers. Eg, Mage Mary tries to see the aura of Beast Betty while Betty tries to go unnoticed. Mary can only see the aura if Betty is noticed, and Betty can't go unnoticed if Mary is studying her aura. Thus, Clash of Wills to determine who wins.
AFAIR, Demons do not have an easy way to pierce supernatural illusions (like Vampires' Obfus-"don't look at me"-cate.) However, I'm including it as an option because it would make sense.
A "see through illusions" power would likely be a custom Exploit, though - from the GM's perspective, seeing a "normal human" perfectly watch an invisible Vampire would sure seem abnormal, and surely be flagged for later review.
No.
[Disclaimer] I do not own Demon: The Descent.
I would rule that being in Twilight (or the Astral Realms, etc) is not a matter of physical distance, but metaphysical distance. A power worded "view the target wherever they are" would be allowed to view across dimensions.
Depending on the source of the intangibility, one is not necessarily invisible. If the invisibility is natural, I would rule that the Demon could sense the location but not see the individual (thus, knowing the power worked). If supernatural concealment is in use, consider Clash of Wills.
Optional: If the power requires a roll, consider allowing exceptional successes to pierce through into other dimensions if needed.
