The Observant feat states:

You have a +5 bonus to your passive Wisdom (Perception) and passive Intelligence (Investigation) scores.

To my knowledge, nowhere else in the rules is there discussion regarding a passive Intelligence (Investigation) score.

Furthermore, on D&D Beyond, the Passive Intelligence (Investigation) is included under the character's Senses akin to Darkvision or Blind Sight.

Several illusion spells include language along the lines of:

Can use its action to (do something to see through the illusion) and must succeed on an Intelligence (Investigation) check against your spell save DC.

Does the creation of a Passive Intelligence (Investigation) by the feat constitute a scenario of specific beats general rule whereby any illusion that can be defeated by an investigation check automatically fails if the save DC is lower than the passive score created by the feat?


1 Answer 1



Specific beats general in this case would apply to the spell description specifying that an action is required to investigate the illusion.

The general rule is that an ability can be used passively, which is true whether a character has the observant feat or not.

The popular passive Wisdom (Perception) check is actually just one example of many possible uses of the general Passive Checks rule PHB 175.


A DM at their discretion may decide that any character has sufficient intelligence to discern reality from illusion. Encountering illusions in a particular campaign maybe sufficiently routine that the DM decides to use the Passive Check rule, and in such a case the observant feat may aid in overcoming the illusion.


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