The Inquisitive rogue's Eye for Detail feature allows bonus-action Perception checks. Would that negate disadvantage on attacks when heavily obscured?

Question

The Inquisitive rogue subclass allows Perception checks as a bonus action. Would that remove or affect disadvantage on attacks in a heavily obscured area during combat?

Let's say an Inquisitive rogue is in a fog cloud. By my understanding, advantage and disadvantage cancel out if you are fighting someone else in that cloud. But if you were able to make a Perception check as a bonus action (and succeed) before attacking, could that negate your disadvantage?

As far as I can tell, there are no direct rule applications, but I just wondered if I'm missing something. I guess in my head, using your action to search for someone when you can't see due to environmental conditions them isn't that useful for attacking purposes. But if you were to use a bonus action (in effect, searching and attacking nearly simultaneously), would that change anything?

Same question for attacking from outside the heavily obscured area. I search as a bonus action, find, and shoot an arrow at the enemy - would that negate my disadvantage?

Answer 1

Unfortunately, it does not quite work that way

The rules for unseen attackers and targets state (emphasis mine):

Combatants often try to escape their foes' notice by hiding, casting the invisibility spell, or lurking in darkness.

When you attack a target that you can't see, you have disadvantage on the attack roll. This is true whether you're guessing the target's location or you're targeting a creature you can hear but not see. If the target isn't in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target's location correctly.

When a creature can't see you, you have advantage on attack rolls against it. If you are hidden — both unseen and unheard — when you make an attack, you give away your location when the attack hits or misses.

A Perception check will not make something that is unseen become seen, so the disadvantage will remain.

As you state, if the creature is blind to you as well, then your attack gets advantage, which cancels out the disadvantage and results in a normal attack roll (a single d20 roll).

So how can a Perception check help?

As mentioned in the quoted text above, if you are unaware of the target's location, you can attempt to guess their location and attack. However, you may miss; if you do, you will not know whether you guessed correctly or not.

If the target you are fighting in fog chooses to hide or you lose track of their location, your DM may allow you to make a Perception check to find them again (possibly contested by their Stealth if the target is hiding). Normally this would take an action, but as an Inquisitive rogue you could do this as a bonus action, allowing you to attack their known position on the same turn.