Can Force effects from the Border Ethereal affect targets on the Prime Material?

Question

According to the DMG, force effects extend from the Prime Material Plane into the Border Ethereal (DMG, page 48):

A traveler on the Ethereal Plane is invisible and utterly silent to someone on the overlapped plane, and solid objects on the overlapped plane don't hamper the movement of a creature in the Border Ethereal. The exceptions are certain magical effects (including anything made of magical force) and living beings.

Is the opposite also true? If I'm on the Ethereal Plane, can I cast Forcecage, Eldritch Blast, Magic Missile, etc. on a creature on the Prime Material Plane, and it will have the intended consequences?

Answer 1

Apparently, Not damage

I asked this question to Jeremy Crawford on Twitter. The answer was a link to a previous tweet he left someone else which was at the time an official rules clarification and no less true now that it isn't an official ruling:

No general rule causes force damage to pass from one plane of existence to another. #DnD

So, force damage doesn't pass either way across planes.

Answer 2

Actually, if we back up a few sentences, this cleans itself up quite nicely.

Page 48 of Dungeon Master's Guide:

Normally, creatures in the Border Ethereal can't attack creatures in the overlapped plane, and vice versa.

So, you're out of luck with Magic Missile and Eldrich Blast (since they're both attacks) unless you've got some rule that lets you attack between planes like a Ghost or Banshee (I may be thinking of Pathfinder on those examples). However, get cozy with that dimension-defying force cage if you're trying to be sneaky and stop someone, because that puppy specifically isn't an attack and he's reaching out and touching that someone.

Answer 3

Yes they can.

Normally, creatures in the Border Ethereal can't attack creatures on the overlapped plane, and vice versa. A traveler on the Ethereal Plane is invisible and utterly silent to someone on the overlapped plane, and solid objects on the overlapped plane don't hamper the movement of a creature in the Border Ethereal The exceptions are certain magical effects (including anything made of magical force) and living beings.

However targeting might be troublesome.

From the Border Ethereal, a traveler can see into whatever plane it overlaps, but that plane appears muted and indistinct, its colors blurring into each other and its edges turning fuzzy. Ethereal denizens watch the plane as though peering through distorted and frosted glass, and can't see anything beyond 30 feet into the other plane.

Dungeon Master's Guide, page 48

Answer 4

As far as I can see, there is no general rule that suggests that a creature in the border Ethereal can affect another creature on the plane that it borders. Equally, there is nothing in the rules that prevent you from targeting a spell or other effect into another plane subject to the normal limitations like range etc.

Therefore it comes down to individual cases:

• Forcecage No - the effect extends into the border Ethereal, there is no suggestion that it extends from the Ethereal into the other plane. However, there is nothing in the spell description that prevents you from targeting the spell at a point in the other plane

• Eldrich Blast Yes - the target is "a creature within range"; what plane they are on is irrelevant. Note you can shoot this further than your 30 foot range of vision (with disadvantage).

• Magic Missile Yes - the target is "a creature you can see within range"; again, plane is immaterial, however, you are limited to creatures you can see.

• and so on.

This is different from previous editions! If you want to house rule that a force effect is on both planes in all cases then that's fine but in 5e what it says is what it means and if it doesn't say it, it doesn't mean it.