Searching for how to handle all surprise scenarios, I still have one question.
Say that the PC is sneaking up on enemies/enemy and silent-cast Dissonant whispers.
You whisper a discordant melody that only one creature of your choice within range can hear, wracking it with terrible pain. The target must make a Wisdom saving throw. On a failed save, it takes 3d6 psychic damage and must immediately use its reaction, if available, to move as far as its speed allows away from you. The creature doesn’t move into obviously dangerous ground, such as a fire or a pit. On a successful save, the target takes half as much damage and doesn’t have to move away. A deafened creature automatically succeeds on the save.
It is my understanding that initiative is rolled before any attack takes place.
The enemies with a higher initiative would likely end up not doing much on their turn, they still don't know they are in combat (or are we rolling for surprise directly after initiative?).
Then the PC proceeds attacking normally with no advantage, since Dissonant whispers doesn't have an attack roll.
The target is now painfully aware of that he is being attacked. And under normal circumstances, so are his friends.
My assumption is that they are now actively searching for the attacker, as opposed to passively, making stealth much harder. But beyond them moving about and actively searching, no one should know where the attack was coming from, thus not rushing to attack.
Or do we roll stealth again against passive perception, to determine if they are surprised? And if they are, will they wait a turn with trying to actively search for the PC? Or do they just know where he is the next turn?