How does a gelatinous cube's special ability engulf work?

Question

The gelatinous cube possesses the extraordinary ability engulf that says

Although it moves slowly, a gelatinous cube can simply mow down Large or smaller creatures as a standard action. It cannot make a slam attack during a round in which it engulfs. The gelatinous cube merely has to move over the opponents, affecting as many as it can cover. Opponents can make opportunity attacks against the cube, but if they do so they are not entitled to a saving throw. Those who do not attempt attacks of opportunity must succeed on a DC 13 Reflex save or be engulfed; on a success, they are pushed back or aside (opponent’s choice) as the cube moves forward. Engulfed creatures are subject to the cube’s paralysis and acid, and are considered to be grappled and trapped within its body. The save DC is Strength-based and includes a +1 racial bonus. (Monster Manual 203)

Can an answer walk me through the turn of a gelatinous cube that wants to use this special ability?

I mean, so it's the cube's turn and the cube takes a move action to get nearer its foes then it takes a standard action to… do what exactly? Does it take that standard action to continue moving into the occupied squares of as many foes as its 15 ft. speed allows, potentially engulfing every foe in its path with no maximum as to the number of creatures that can be engulfed? (And hilarity ensues!) Does it take that standard action to engulf but one adjacent creature by moving into that creature's space and covering the creature, a result that seems disputed by the description of the engulf ability? Or does something else happen that I'm totally overlooking?

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Note: The last cube I ran was a Gargantuan cube advanced to 24 Hit Dice partnered with a Huge advanced Monster Manual mimic (186) in a high-level adventure. However, the pair just hit and grappled foes, the cube never engulfing. While doing some reading, I was pointed at the ninth and final issue of the ex-Wizards of the Coast messageboard-sponsored Knowledge Arcana PDF e-zine that includes the prestige class adamantine chef. (For those interested, previous Knowledge Arcana issues are available by changing that issue #9 URL from 09.PDF to 08.PDF and so on, and also available is the nominal 3.5 update of the pie fiend that's issue #9's PDF Web extra.) Included in the prestige class article is a new monster that can be summoned by the adamantine chef: the death salad (I'm not even kidding)… that has the same special ability engulf as the cube. In trying to summarize the death salad's engulf ability for personal use, I realized I had no idea how the ability worked and that the cube's ability worked in an identically baffling fashion.

Also, while several 5e questions have been posed about the cube's engulf ability, only this one is really about the 3.5e cube and its engulf ability, but it's about how much damage the cube deals after it's engulfed a hapless foe rather than how the engulf ability works.

Answer 1

The move action and the Engulf's standard action are separate.

By virtue of the comment:

"The gelatinous cube merely has to move over the opponents, affecting as many as it can cover"

...it is apparently allowed to move into the spaces of opponents. If any creatures it wants to engulf is in the covered space at the end of it's move, it can then take a standard action to engulf whatever creatures are in the target area. (By changing the permeability of it's membrane, maybe?) If they succeed on the reflex save, they are instead pushed back or to the side (opponent's choice).

Creatures that fail are now "engulfed" and are thus in a legal positioning at the end of the cube's turn. Creatures that succeed on the save are "pushed back or to the side", and are also thus in a legal positioning at the end of the cube's turn.

Should it not choose to engulf, then it would be subject to the standard movement rules and have to end it's turn in a legal space.

Example:

1. Cube's turn.

2. Cube decides to take engulf action during it's turn as snacks are in range.

3. Cube takes move action. This move may end in squares overlapping opponents if and only if it is going to take an engulf action during this turn. This movement will trigger AoO's only if the movement would normally trigger by the AoO rules.

4. Cube takes standard action to activate engulf. This triggers the option for Reflex save OR AoO per the Engulf ability, which may have nothing to do with movement triggered AoOs.

5. Everyone ends up either inside the cube taking damage, or pushed back or aside to a legal position and not engulfed.

6. End of Cube's turn.

Answer 2

It engulfs whoever it moves over with its 15 foot movement.

Your gargantuan cube is 20 feet wide- if it moves directly forward for 15 feet it will engulf anyone standing in the 20 x 15 foot area directly in front of it - potentially 12 medium sized creatures.

Answer 3

As far as I can tell, gelatinous cube's Engulf ability is a successor of Trample ability. You may probably reffer to Trample for every aspect not covered by Engulf's own description.

First of all, Trample was changed between D&D 3.0 (and gelatinous cube already was there) and D&D 3.5. Back then in D&D 3.0 Trample worked mostly like Engulf works now.

So a turn of a cube would look like:

1. It may choose to use its move action to close up if necessary.
2. Engulf itself provides a portion of movement equal to a cube's land speed.
3. While Engulf specifies "large or smaller opponents", the description most probably intended to say "same size or smaller opponents". When the cube uses Engulf it may "mow down" everybody whose space it passes through during its movement gained from Engulf given those creatures are of a valid size.
4. If it for some reason hasn't already used it's move action, it may now use it taking everybody it engulfed with it.

It is my assumption, but gelatinous cube may not probably simultaneously engulf more opponents than it can cover with it's space (i.e. their spaces have to be able to be housed inside its space).

You may also consider to rework Engulf special ability to match new mechanic of Trample, but it is utterly up to you.

Answer 4

Overrun, oozy, squishy overrun

Per its description, the base, 4-12 HD gelatinous cube's space is 10', its reach is 5', and its described size is 15' per side. Higher HD cubes' aren't described, but they may overflow their space in a similar fashion; if so, the Huge cubes might be 20' on a side, considering their 15' space, and 10' reach. The cube already kind of 'occupies' the space of creatures it's 'adjacent' to.

[... A] gelatinous cube can simply mow down Large or smaller creatures as a standard action. It cannot make a slam attack during a round in which it engulfs. The gelatinous cube merely has to move over the opponents, affecting as many as it can cover. Opponents [that succeed at their saving throws] are pushed back or aside (opponent’s choice) as the cube moves forward

^{[Emphasis mine]}

Overrun (PHB, 157)

You can attempt an overrun as a standard action taken during your move. (In general, you cannot take a standard action during a move; this is an exception.) With an overrun, you attempt to plow past or over your opponent (and move through his square) as you move. You can only overrun an opponent who is one size category larger than you, the same size, or smaller. You can make only one overrun attempt per round.

^{[Emphasis mine]}

The cube simply engulfs during its move action, the move action having the engulf 'kicker' added on like a much squishier, and harder to avoid, overrun. It moves into the creatures' space, and they can either take the provoked attacks of opportunity, or try to dodge out of the way. The cube's Engulf ability is kind of like a different form of Improved Overrun (which usually forbids dodging, but still allows for the AoO), though it may overrun as many creatures as it can move over in one round, and it's limited to Large or smaller (rather than 1 size larger than its own). It's the overrun ability, writ large. And like I said before, significantly squishier.

The attack would look like this:

Step 1: Defender chooses whether to take an Attack of Opportunity, or attempt to avoid. By moving into the defender’s space, the cube provokes an attack of opportunity from the defender, but the defender can't both attack and avoid. If the defender attacks, unless the attack results in the cube's death, or somehow prevents it from moving, go to step 3, otherwise go on to step 2.

Step 2: Opponent Avoids? If the defender succeeds at a reflex save to avoid the cube, he is moved by the cube, choosing whether to move aside, or be pushed in the cube's direction of travel. If the opponent doesn’t avoid the cube, move to Step 3.

Step 3: Opponent Engulfed. Engulfed defenders are grappled by the cube, are subject to its paralysis ability, and are trapped inside, moving with the cube. Defenders who are not paralysed can attempt to grapple the cube, or other actions available to them in a grapple.

As to the number of creatures that it can engulf, either simultaneously, or serially, the ability lists its ability to cover them as the limit. It's unclear whether the 15' dimension of the description or the 10' space of the listing should be the limitation, but the cube would have to 'cover' a creature's entire space in order to engulf it. The standard gelatinous cube could therefore cover up to one large creature during a single engulf, at least 4, and as many as 9, ground based medium creatures, and as many as 8 (or 27) if they were in a closely packed aerial formation. A huge cube could engulf 1-4 (depending on size stat vs described dimensions again) ground-based large creatures, 1-8 in flying formation, 9-16 medium ground-based creatures, and 27-64 in flying formation. The engulf ability of Huge cubes could reasonably be extrapolated to cover Huge or smaller creatures, but it's not explicitly stated.

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I'd suggest that, as the cube's engulfed victims are paralyzed and grappled by the cube, it could move them about within itself, and thus could really 'pack them in'. It's 15' on a side, or 3375 cubic feet. a Huge cube might be 8000 cubic feet. If a human is 6'x2'x1' then as many as 280 could eventually get packed into the Large cube, and maybe 666 into a Huge one. Presuming a horse is 5'x6'x3', then perhaps up to 37 could be engulfed at a time in a Large cube, and up to 88 might fit inside a Huge one.

While the specific cubic measurements of a human or horse might be debatable, the cube has an enormous capacity to both gobble them up, and keep them while they digest.

Answer 5

I read the first part of the description as "As a standard action, the cube moves over some opponents and engulfs them".

This means that the cube also gets a regular movement action.

Answer 6

I have always interpreted the rules such that:

1. Engulf is a standard action.

2. The Gelatinous Cube (GC) must have enough movement to occupy at least one square that contains another creature (Large size or smaller) without taking more than one move action.

3. If the GC uses its movement to occupy 1 or more creatures square(s), then it has to use its standard action to make an Engulf attack. Otherwise, it would not be able to occupy another creature's square.

4. Creatures that could potentially be engulfed have the option to make an AoO, but are automatically engulfed in the GC, if the GC survives the AoOs.

5. If the GC uses two move actions to occupy the PC's square, the GC would not be allowed to engulf this round. If it is still sharing any squares with another creature at the start of its next turn, it will immediately try use an Engulf attack.

The Engulf action does not grant any extra movement, but is automatically activated when its movement ends in one or more occupied squares.