Imagine a hallway, 10 ft wide and 10 ft tall, such that the Cube completely fills it, as per its Ooze Cube trait. Immediately adjacent to the Cube are 2 Medium creatures, which span the width of the hallway by taking up 5 ft each, and immediately behind them are 2 more Medium creatures, again spanning the hallway. The hallway is clear behind this second row. On its turn, the Cube moves up to 15 ft and will attempt to Engulf all 4 Medium creatures as it travels.

How should the Engulfing be resolved?

For reference, this is the relevant text of the Cube's Engulf action (emphasis mine):

The cube moves up to its speed [15 ft]. While doing so, it can enter Large or smaller creatures' spaces. Whenever the cube enters a creature's space, the creature must make a DC 12 DEX saving throw.

On a successful save, the creature can choose to be pushed 5 feet back or to the side of the cube. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.

Notably, in this situation, the Medium creatures cannot be pushed to the side (since the Cube fills the entire hallway) and it seems those in the front row cannot be pushed back (as Jeremy Crawford states "you can't willingly end your move... in another creature's space").

Some possibilities:

  1. The Cube moves 5 ft and attempts to Engulf the first row of creatures. They automatically fail their save, because they have nowhere to go. The Cube continues to spend movement, going another 5 ft forward and attempts to Engulf the second row, which attempt their saves as normal. Does this count as 2 uses of the Engulf action or 1 continuous use?
  2. The Cube moves 5 ft and attempts to Engulf the first row of creatures, which make their saves as normal. On success, the entire group is pushed back, with the first row effectively forming a moving wall between the Cube and the second row.
  3. As the previous possibility, but as the group retreats, the Cube continues to move the full 15 ft forward, forcing those in the front row to make up to 3 saves each as it advances. This one seems intuitively to be multiple uses of the Engulf action rather than a single continuous action.
  4. The Cube moves 5 ft and attempts to Engulf the first row, which make their saves as normal. On success they are pushed back through their allies, effectively swapping the rows. The new first row then makes their save against the Engulf as the Cube continues to move forward.
  5. The Cube moves 10 ft (through the first row) and attempts to Engulf all 4 creatures simultaneously. They all make their saves at once, and those that succeed are pushed backwards as a group, relative to where they started.

3 Answers 3


The key word for me here is "willingly."

They're not "willingly" being pushed back into another person's square. They're being shoved back by a Cube in an attack.

I'd say that shove means if they pass, the row 1 people effectively shove the person behind them back as well. Possibly causing them both to fall, as person in row 1 column A collides with person in row 2 column A.

But you can't look at the action at the level of the Row. You must look with more granularity.

I would look at it like this:

  1. Person in Row 1 Column A (r1cA) passes her save and is forced back five feet. This means the cube can move forward into that square. More on where she goes in a moment.
  2. Person in Row 2 column B (r2cB) fails his save. He is engulfed and the cube can move forward into that square.

So that's the first piece. The cube has advanced 5 feet, engulfed 1 person and driven 1 person back.

  1. person r1cA is now in r2cA's square. Oops. r2cB now needs to save or trip. r1cA probably needs to do the same. If they fall, can they still make saves against the engulf? Or just at negatives?
  2. person in r2cB is threatened and makes his initial save. Pass or fail, doesn't really matter to the Cube; it advances.

At this point, the Cube advances into row 2's range. r2cB can either save of fail; doesn't really matter to this discussion. What matters is how r1cA and r1cB are treated.

As a GM, my play here would be a save against falling for both of them. If they fall, then they're prone and at much greater risk of engulfing. If they pass and still standing, then they are shoved back out of the way.

  • \$\begingroup\$ How should the rest of the Cube's movement be resolved? If Row 1 succeeds, and stumbles back into Row 2, potentially prone, and the Cube continues to advance (it has 10 ft of movement left), do they now all make DEX saves again? If they all pass again, would they be forced to do it a third time as the Cube keeps moving forward? \$\endgroup\$ Feb 6, 2017 at 19:07

The simplest way to do this is your choice 5.

(Note: your option 5 posit only a 10' move. If it had enough movement, it could move 15 feet ... so it if started a bit further from the group it could still engulf them all with a full move).

The point I'd emphasize is that the party isn't impeding the movement, due to their size. Its moving, and they've got to deal with it.

While doing so, it can enter Large or smaller creatures' spaces.

Using the basic framework of the turn based game (based on the initiative order1) the cube carries out its action and any result of that action is resolved.

This prevents slowing down play and reflects both the spirit of the rule and the letter. Using initiative, the cube's actions take place before/after the party's actions. Because it can move into squares with creatures of their size, the simplest command to give it, as DM, is to move it however far it can/wants to, and see who has to save. (Just like, if an evil mage casts fireball on his turn, the PC's roll a save as part of his action being resolved).

Once they roll, see who saves. Whomever saves is outside, pushed back as you describe. Whomever didn't is inside.


The caveat I'd add to that is if any character has a ready action that would influence the result. That would mean that "being swallowed by the cube" (or "the cube moves into my square" or something like that) is the trigger for a readied action.

The question for you is: how many additional rolls you (as DM) want to add to the encounter to add to granularity. I recommend the KISS principle, as it adheres to the fundamental play model (p. 3 Basic Rules):

  1. DM describes environment / what's happening.
  2. Players describe action (in this case, substitute in "roll dex saving throws")
  3. DM narrates the result.

Clean, simple, and it keeps play moving.

What if 3 of them make the save?

The simple way to resolve:

The DM chooses who ends up behind the other based on

  1. your own judgment

  2. or a random chance

    For the random chance, toss one d6.

    • Let an odd result mean that whomever was in front ended up behind the other(That's odd, how'd I end up back here?)
    • Let an even result mean that both get bumped back (due to the mad scramble to avoid getting engulfed) and end up as they were oriented before the cube moved.
    • This die roll method provides a quick resolution, reflecting both DM impartiality and the chaos during that turn attending the mad scramble (Dex Save) to avoid getting engulfed by the inexorable advance of the cube!

1 Initiative

Initiative determines the order of turns during combat. When combat starts, every participant makes a Dexterity check to determine their place in the initiative order. ... The DM ranks the combatants in order from the one with the highest Dexterity check total to the one with the lowest. This is the order (called the initiative order) in which they act during each round. (p. 69 Basic Rules)

  • \$\begingroup\$ I like this answer, but... What happens if the cube started 10' away, so it can only engulf the first row? Where do those who made their save end up? \$\endgroup\$ Feb 6, 2017 at 22:40
  • \$\begingroup\$ That isn't how the question was phrased, was it? I was under the impression that the cube had enough movement to hit them all. (Did I misread the question?) \$\endgroup\$ Feb 6, 2017 at 22:41
  • \$\begingroup\$ Maybe I'm digressing into a larger question than was asked, but the case where someone makes the save and has to move 5' but has no empty space into which to move seems important. \$\endgroup\$ Feb 6, 2017 at 22:43
  • \$\begingroup\$ That's where the "willingly move" issue calls for a DM ruling when the PC who makes the save. If one in the back row misses, then just slide into that spot. If both save, either push one in the back further back, or have the "unwilling" move include movement through a friendly creature's space (which you can do ... you just can't end your turn there) . Either one works. \$\endgroup\$ Feb 6, 2017 at 22:45

There is another option. The cube moves forward, attacking all four. It has essentially plopped itself onto all four. Each creature attempts to escape. If successful, those in the first row pop out behind the cube (they moved forward) and those in the second row pop out in front of the cube (they moved backwards).


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