[RPG] Is a creature with Blindsight affected by illusions


Is a creature with Blindsight affected by illusions? For example, would a bat familiar be able to see through a Disguise Self spell?

My understanding is that it can certainly "see" through invisibility. My feeling is that immaterial visual illusions, like Silent Image or Disguise Self, should be transparent to blindsight, but I'm not sure if that's consistent with RAW.

Best Answer

No, except at higher levels.

While there is no specific rule, I would say this is a reasonable interpretation. Creatures with blindsight "can perceive its surroundings without relying on sight, within a specific radius". It seems that most blindsight works on some physical interaction with the object (hearing echoed sound waves for bats, sensing heat for snakes, etc.). Most low-level illusion spells are non-reactive visual and/or auditory illusions, like Minor Illusion and Disguise Self. These spells could not create a illusion that could react to a creature's blindsight in a way that would seem real.

This interpretation seems to be supported by a line in the Blur spell, stating "an attacker is immune to this effect if it doesn't rely on sight, as with blindsight." That said, at higher level, illusion spells can be complex enough to fool certain senses (Major Image) or be able to physically interact with it's surroundings (Phantom Steed).

These are in general cases, of course. Ultimately, it is up to the ruling of the DM whether or not the situation allows the illusion to appear more or less real. For example, maybe you are somewhere where it's really loud and your DM rules that the area is heavily obscured from your bat's blindsight. It would be reasonable to assume that you couldn't sense an object, through echolocation, that you could see visually, so your bat could be fooled by a purely visual illusion (like Disguise Self) in that case. I hope this answers your question.