If the target of the gelatinous cube's Engulf action saves and is pushed 5 feet back, does the gelatinous cube keep moving and force another save?

Question

If the target of the gelatinous cube's Engulf action succeeds on the Dex save and is pushed 5 feet back, does the gelatinous cube keep moving and force the target to make another save?

Let's imagine a scenario: There's a 10-foot-wide hallway, with a gelatinous cube and a creature next to it. The gelatinous cube uses its Engulf action, moves 5 feet and enters the other creature's space. The target then makes a Dex save, rolls a success, and is pushed 5 feet back.

Does the cube keep moving, repeating the process until its 15 feet of movement ends? Or does it just stop after the initial success?

Answer 1

It gets to keep engulfing.

Here's the relevant part of the Gelatinous Cube's Engulf action:

Engulf. The cube moves up to its speed. 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 Dexterity 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.

So what doesn't happen is that it uses its action to try to engulf you, and then can't do it again this turn.

What happens is that it gets to move the entire 15 feet, and attempts to engulf anyone in its path. If it starts its turn within 10 feet of you, and there's no space to dodge out of its path, it can force you to make multiple Dex saves to keep running away.

This is its hunting strategy. The Cube is an ambush predator. It can't catch victims who have any space to run; it needs you to get as close as possible before it moves. The closer you are, the more Dex saves you have to make to escape. It has a few tools to support that strategy:

• Transparency makes it's hard to see when it's not moving.
• Blindsight lets it lurk in poorly lit places where it's even harder to see.
• Its shape lets it block a narrow passage to prevent prey from escaping.

The best case for the Cube is that some sucker blunders right into it. The victim will have to make one save with disadvantage immediately, and then be surprised, which gives the Cube another three tries to engulf them on its turn. So they have to pass five Dex saves back to back. This isn't even an unlikely scenario if it can hide in a dark spot that's accessible to surface-dwellers. If it's in total darkness, it may well be impossible to detect.

Answer 2

I am using the variant from Roll20, as I got no other version handy.

Actions: Engulf. The cube moves up to its speed. 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 Dexterity 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. On a failed save, the cube enters the creature's space, and the creature takes 10 (3d6) acid damage and is engulfed. The engulfed creature can't breathe, is restrained, and takes 21 (6d6) acid damage at the start of each of the cube's turns. When the cube moves, the engulfed creature moves with it. An engulfed creature can try to escape by taking an action to make a DC 12 Strength check. On a success, the creature escapes and enters a space of its choice within 5 feet of the cube.

So it is kinda like a charge towards a specific point. And creatures are just "in the way". Yes, I would propably allow multiple "Attacks" against the same person. The normal engulf rules allow going to the side of the cubes path to avoid that. But here the environment blocks that option.

Gelationous Cubes in a tight corridor are scary as the nine hells. You can not dodge sideways and might run into one by accident.