[RPG] Can Blindsight “See” Through Walls, Floors, And Ceilings

dnd-5eline-of-sightvision-and-light

I am currently play-testing an Awakened Mystic character in D&D 5e, using the draft rules released by WotC. As such, I have an ability that lets me choose between having blindsight or tremorsense.

Blindsight

A creature with blindsight can perceive its surroundings without relying on sight, within a specific radius. (Player's Handbook p. 183)

Tremorsense

A monster with tremorsense can detect and pinpoint the origin of vibrations within a specific radius, provided that the [observer] and the source of the vibrations are in contact with the same ground or substance. Tremorsense can't be used to detect flying or incorporeal creatures. (Monster Manual p. 9)

I have been wondering what the difference is between these two, aside from the fact that tremorsense requires contact with the ground and cannot detect flying or incorporeal creatures. Specifically, I want to know whether blindsight cannot detect creatures through solid matter such as walls, floors, and ceilings, whereas tremorsense can? Can blindsight detect creatures on the other side of a dungeon wall, or on another floor of said dungeon? Are there monsters in 5th edition that possess both blindsight and tremorsense, and if so, when and why would they use one as opposed to the other?

I am aware of and appreciate this question regarding blindsight's capability to detect invisible creatures, but it doesn't exactly address my issue of whether solid matter effectively "blocks" blindsight.

I will gladly consider either rules-as-written or rules-as-interpreted answers. If there is a published game mechanic or a posted developer ruling I have overlooked, please include and cite them in your answer.

Best Answer

Blindsight (monster ability)

A creature with blindsight can perceive its surroundings without relying on sight, within a specific radius. Creatures without eyes, such as oozes, and creatures with echolocation or heightened senses, such as bats and true dragons, have this sense.

This isn't super helpful mechanically, however it does mention 'creatures with echolocation like bats'. Echolocation in real life still requires a line of effect, and wouldn't work through solid walls. This isn't specifically spelled out in the text, but in the absence of a rule we have to take into account the words being used. In this case, a bat would be able to echolocate in complete darkness, but would not be able to echolocate a person on the other side of a 5 foot stone wall. Since the manual doesn't go on to describe echolocation in any greater detail, we have to assume it means in DnD what it means in real life.

It looks like a Purple Worm has both blindsight and tremorsense, which would seem to show that there is a reason to have both, which would again point to the above definition where blindsight does not work through solid objects but tremorsense does.

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