Had a very strange combination happen, can someone help me with the proper ruling? A rogue is fighting a Deculi (Age of Ashes Book 4, Fires of the Haunted City) in a hallway. The Goblin Rogue activates invisibility (action 1) while underneath the flying Deculi and tries to Sneak away (action 2, and he has a feat that allows him to Sneak at his full move speed), moving around a corner and out of sight during that move action, and then draw a potion (action 3). The Rogue has the Very Sneaky feat as well, allowing him to remain hidden with Sneak actions as long as he has cover/greater cover/concealment by the end of his turn.
Here's where it gets weird. The Deculi does not have sight, it has infra-red detection as a precise sense, allowing it to detect body warmth. The rule for invisibility says "You are undetected to everyone". What if the creature does not have sight as a sense at all but has something else, like precise echolocation or precise smell? Are you still Undetected at that moment invisibility activates, or doe Invisibility only affect sight based perceptions?
I ruled that the Rogue was never undetected during action 1. The Deculi has no opportunity attack, but since action 2 (Sneak) took the Rogue around a corner he was out of view at the end of that action. His third action wasn't to sneak again though, it was to draw a potion. I ruled that as not breaking any existing rules of Sneak. But - was he Hidden at either the start or the end of action 2? If you are not Undetected when you begin to take the Sneak action, but are out of sight at the end of that action, are you Hidden?
To make this more complicated, the Rogue has Foil Senses (Whenever you take the Avoid Notice, Hide, or Sneak action, you are considered to be taking precautions against special senses). How does that come into play with Action 1 (activate Invisibility) or Action 2 (Attempt to Sneak)?
I had the Deculi on action 1 move down the hall and around the same corner, as he knew which way the Rogue had moved. The Rogue is just standing in the middle of the room. My planned Action 2 was to Fly to the Rogue and action 3 to attack. I wanted to rule that since the Rogue was in plain "view" of the Deculi, Foil Senses no longer applied as he had no cover or concealment of any kind. He argued that the creature could not see him because of Foil Senses and should not have even known which way he moved in the first place
The way I was interpreting this, if I took Foil Senses at it's literal word, the Deculi could NEVER see the Rogue to being with as all it had was an alternative sense, and that made no sense to me. I stated that if the Rogue were undead, he would effectively be Invisible to the Deculi at all times. He said I needed to make a perception check when I entered the room and if I failed, I'd have to spend another perception check even though the Rogue is just standing in the middle of the room.
So - how should Invisibility with Foil Senses work against a creature that has no sight to begin with? And how does Foil Senses work with Sneak in this case, if the Rogue was not Hidden at the start of that action? I find it hard to believe that the intent of Foil Senses allows you to lower your body temperature to the Underdark temperature. Can anyone help me with the RAW ruling?
