A poster on the dndbeyond.com forums pointed out that some conditions are not absolute, that they exist only with repect to another creature or object. For example, you can be charmed by one foe but not charmed by another.
I like this idea. I think it helps explain away some of the confusion around rules (in particular the idea that if someone using truesight can see you, the invisible condition is cancelled for everyone).
Absolute Conditions
A creature either has this condition, or they don't. The condition applies to all interaction between the creature and its environment.
Anything that ends the condition ends it entirely.
- Blinded (but see below)
- Deafened
- Exhausted
- Grappled (who or what is grappling you is only important for determining when the condition ends)
- Incapacitated
- Paralyzed
- Petrified
- Poisoned
- Prone
- Restrained
- Stunned
- Unconscious
Relative Conditions
Unseen (related to Blinded and to Invisible)
Some game features, for example obscurement, refer to the blinded condition. I think a better phrasing for this is "unseen".
A creature is unseen by another creature if the second creature has no line of sight to the first.
This could be because of concealment between the two (darkness, foliage, fog), because the second creature is blinded, because the first creature is invisible and the second creature has no way to see through this, or because of some other reason.
Having an "unseen" condition removes the need for an "invisible" condition, which I think is a good thing.
It also allows for a condition of camouflage (AKA hidden in plain sight) which 5E has no way of modelling.
Note that if one creature cannot see a second, there are not necessarily any effects on attacks to or from a third creature.
Unheard
An "unheard" condition could interact with a few game features (for example Bardic Inspiration).
Charmed
The effects only apply to interactions with the charmer.
Frightened
The effects only apply to interactions with the source of fear.
Turned
5E does not list "Turned" as a condition, but I think it should. It works much the same way as Frightened.
Hidden
5E does not list "Hidden" as a condition, but I think it should. It works much the same way as Invisible.
If creature A is Hidden from creature B then B does not know A's location or even whether or not A is present.
As with unseen and unheard, the fact that A is hidden from B does not mean that A is hidden from another creature C.
If C knows A's location and communicates this to B then A will no longer have the Hidden condition with repect to B.
