DM Livgin wrote:
What does an invisible scrying sensor look like?
Humor aside, I don't think its specified anywhere what it might look like if percieved by someone, its up to the DM and might vary by spell used as well as by who was the caster. Most of the time I think it is envisioned as invisible floating eyeball of some sort but ...
DMLivgin wrote:
What does a player character notice with that DC 24 perception check versus the scry spell?
Going to extend the question/answer a bit to any sensor and not just the sensor created by the Scry or even Greater Scry spells in particular.
Note that the DC for the perception check can/could be just the baseline. Range modifiers could be applied. It's not clear to me if the 20 in the 20+spell level is for being invisible or if mods for motion or lack thereof could be applied as well. The sensor can be either in motion or not --> such as with Arcane Eye which can be in either state when a Perception check is made. Other visibility conditions could also apply (Darkness, Fog, weather etc.). Strictly speaking what they notice/perceive is the invisible sensor. They do no know who or what is being viewed (or the target of) by the sensor. That would be dependent on if a save is allowed and if it was made among other things. Some of those other things would be other spells or effects such as See Invisibility, True Seeing, Invisibility Purge, Detect Scrying, Glitterdust, Nondetection, Mind Blank, etc.. The DM might decide you could tell which direction the sensor was viewing ("the eye you have noticed appears to be staring at you and your companions from across the common room of the tavern") so if it is staring in the characters direction then follows you as you get up and exit the area then I'd say you should have a clue what it is observing. On the other hand nothing says the sensor is spying on the characters it could be spying on the bartender or the King's Councillor who is across the room in a private booth etc..
DMLivgin wrote:
Is it cheating the character out of knowledge if it is just 'a sense of being watched'.
I think that is a separate issue or question and depends a bit on if they are the target of the spell or not, if a saving throw is involved, if it was made or failed, etc., all of which also depend on which spell created the sensor. I think the rules really don't address it clearly, perhaps assuming the perception check will be made anytime one could notice it ... sort of the way trapfinding or secret doors checks occur.
DMLivgin wrote:
Should they have to pass a DC 24 knowledge arcana check (Identify a spell effect that is in place) to realize that they are being scryed on?
Sort of. Almost any character I'd think would be quick to think it must be a magical effect and wonder what is it and what is it doing. So yes that is the mechanic for answering those questions. On the other hand experienced characters even if they can't identify it specifically as spell 'X' should have a reasonable idea that such effects exist and this might be the result of such magicks ... especially if the DM describes it as looking like an eyeball that follows your movements or glances about the area etc..
