A Frightened creature suffers the following effects:
- A frightened creature has disadvantage on ability checks and attack rolls while the source of its fear is within line of sight.
- The creature can't willingly move closer to the source of its fear.
An Invisible creature has the following benefits:
- An invisible creature is impossible to see without the aid of magic or a special sense. For the purpose of hiding, the creature is heavily obscured. The creature's location can be detected by any noise it makes or any tracks it leaves.
- Attack rolls against the creature have disadvantage, and the creature's attack rolls have advantage.
What happens if the source of a creature's fear is invisible or hidden?
- A Wizard uses Cause Fear to frighten an Ogre, then puts on a Cloak of Invisibility. On the Ogre's turn, he tries smack a Fighter standing next to him. Does the Ogre have disadvantage on the attack roll?
- On her next turn, the Wizard Hides from the Ogre. When the Ogre tries to smack the Fighter again, is anything different?
Here are two related questions that may help answer this one:
- This question asks if the frightened creature can avert or close their eyes to avoid the disadvantage. The answers articulate the difference between line of sight and being able to see a creature. Does anything change if the source of the fear is invisible?
- This question asks if the second bullet point of the frightened condition allows a frightened creature to "supernaturally" detect the location of the source of its fears. Would the first bullet point of the frightened condition allow a frightened creature to supernaturally detect the presence of its fears?