Finding invisible creature in combat - an action?

[stenver]

So I read MM and it occurred to me that dragons can take Detect as a legendary action. Then i also found the "Search" action.

So how would one PC spend a round looking for an invisible creature? Or lets assume the PC is blind. Does he need to take search action to spot the enemy? What if the enemy moves after he finds him?

So far, i have just let the PC-s roll a perception and if its good enough, i give them general direction. If its very good, they can pinpoint and attack the enemy - in the same round.

[iTreeby]

If the enemy has not take the hide action , a blind character knows what square the enemy is in. If the enemy has taken the hide action and his result is lover than the passive perception of the blind character, he knows what square the enemy is in. If the enemy has taken the hide action and his result is higher than the blind characters passive perception the blind character must make a perception check to know what square the enemy is in.

[Mjolnirbear]

Hiding and sight is very much up to the dm. There are huge arguments raised everywhere. It boils down to "does it make sense to the DM? The sure you can do it"

The rules: if you can't see him, you get disadvantage to attack. Even if you located him; even if you locate him with a natural 20". He gets advantage to attack you, unless he is also blind (such as heavy fog or darkness).

Unless you have tremorsense, blind sight or true sight. Then even if you are blind you can still 'see' him.

If it's dim light you can try to see him: disadvantage on perception checks based on sight. You succeed, then you can see him. You don't, then you can't.

Many creatures have Keen Senses that allow them to sniff or hear you. They get advantage on sniff or hearing tests. By the rules if they can't see they still get disadvantage; but it's reasonable for a DM to decide that such a creature has senses sufficient enough to attack without disadvantage even when blind. It's also reasonable not to; it's up to your DM.

Someone that hides has his roll countered by perception. If you are blind, you need a way to perceive him before you can roll. Hard to think of a way to do that. If he is invisible, you can toss flour around and try a perception roll.

[stenver]

Thanks for the responses!

[ThermalSlapShot]

I allow a use item action to sweep 5' away from the PC. Usually only 15' worth of movement (3 squares).

If they choose a square that has the invisible creature in it they can tell there is a creature due to movement sound, brushing up against the target with their weapon, or some other thing that makes sense at the time.

Use an item action is free 1/turn and then becomes an action. Rogue (Thief) can use both of those options or make it a bonus action of course.