Casting spells while out of hearing and sight

Question

There are other questions addressing how casting attack spells while hidden blows your cover, but what if you are out of the range of perception for the target?

Some additional background: based on the DM screen, the typical range of sound perception is 35' for people trying to be quiet, 70' for normal volume, and 350' for loud sounds. Firing a longbow creates a sound that's ~90 dB and sound drops off rapidly with the square of distance. By 90', the sound would be no louder than a close distance conversation. At maximum longbow range it would be quieter than any ambient noise.

If I have 120' dark vision range and cast a spell at someone at that range without dark vision (which is "normal" sound), there would seem to be no way they can perceive me and thus reveal my location. Even though I would "no longer be hidden" that only applies to individuals near enough to either hear or see me. Depending on the spell, they might be able to intuit a direction for the attack but not a clear source. Some spells (Chill Touch, for example) create a visual effect at range but do not provide a clear visual link between the spell effect and the caster.

Would a setup like this potentially allow for "spell sniping" someone in the dark without revealing your location?

Answer 1

When you make an attack, you give away your location

Just because someone cannot see your location does not mean they do not know where it is. This is actually the intro to the rule section

Combatants often try to escape their foes’ notice by hiding, casting the invisibility spell, or lurking in darkness. [...] If you are hidden—both unseen and unheard— when you make an attack, you give away your location when the attack hits or misses.

The rule is simple: if you make an attack while hidden, you give away your location. It is not requried that the other creature can see or hear you.

The DM of course can make special exceptions for unusual circumstances, but even narratively, when you attack from out of sight often you still would give pretty good indications on where you are, as the victim may figure this out based on the direction and angle of the missile or spell effect.

The rules are a bit simplistic here. For example, while you are invisible but not hidden, by the rules other creatures cannot see you but still can pinpoint exactly where you are, even if you are far away and it is unlikely they could really do this from sound, which only would give them an idea of direction, if that. Like always, if the mechanics of the rules do not seem to make sense, it would be up to the DM to step in and overrule them.