Can I save immediately against Otto's Irresistible Dance, and have a chance of never dancing at all?

Question

Otto's Irresistible Dance has two components relevant to this question:

A dancing creature must use all its movement to dance

And

As an action, a dancing creature makes a Wisdom saving throw to regain control of itself.

But which happens first? Does the creature immediately use up all its movement on its turn, or can it choose to spend its action to make the save first and thereby avoid ever dancing?

Edit: More exactly, is the use of the wording "must use" sufficient to override the specific rules that allow creatures to take their movement whenever they choose?

Answer 1

You can make your save before losing your move...

From the text of the spell (PHB 264, emphasis mine):

A dancing creature must use all its movement to dance without leaving its space...

Note the term "use" rather than something like "lose" or "have its speed reduced to 0". The spell compels you to move your speed within a 5 foot square. Fortunately, from the description of a player's turn (PHB 189):

You decide whether to move first or take your action first.

Even better, if slightly contradictory (PHB 190):

You can break up your movement on your turn, using some of your speed before and after your action.

In this edition, players are given a great deal of latitude on when to use their movement. Since dancing is a use of that movement, you can choose to save before using it up.

It helps to think about what limits your movement speed under regular circumstances. Remember that a round, and thus a turn, lasts ~ 6 seconds. When your move speed is 30 feet, it doesn't mean you are out of breath after running 30 feet, it means that it takes you about 6 seconds to move that distance with enough time left over to do something else. Dancing keeps you from moving anywhere as the clock ticks down, but if you make your save quickly, nothing in the wording of the spell suggests you would be prevented from using the remaining time in your turn to move your speed.

...but you still dance

You start dancing as soon as the spell is cast, with all of the attendant detriments (disadvantage on attacks and Dexterity saves, granting advantage to attackers). There isn't much you can do about that until the start of your turn, but at least you don't have to stay immobilized.

Answer 2

Short answer

Your very good question has two parts, and the second part is easiest to answer:

The creature cannot completely avoid dancing, as it begins dancing on the caster's action, and can only resist as an action on its own turn.

The question about movement and dancing on its turn seems chicken and egg, but I think the most natural reading of the spell is that all movement is exhausted on dancing, but the creature can make another action, either an attack or a saving throw to break free.

I argue this on two counts:

• the strongly-worded nature of the dancing rule
• the order of the rules as given within the spell

Ultimately however, this point is moot, and up to your DM's judgement.

The strongly-worded rule on dancing

I argue this on the basis of the strong wording of the statement about the dancing:

A dancing creature must use all its movement to dance...

This is the only use of must in the spell description, and the use of "all" makes the statement all the stronger. As the creature is dancing just before its turn, it is reasonable to assume it is a "dancing creature" as its turn begins, so it must use all its movement to dance.

The order of the rules in the spell description

The above strongly-worded statement comes before the action options:

...and has disadvantage on Dexterity saving throws and attack rolls.

The text about the possible saving throw comes at the end of the spell description, which suggests it is an alternative to the attack action, and so that like this action it can only be used once the creature's movement has been exhausted by dancing.

Your DM might not agree

I am aware there are some holes in my reasoning, and if your DM is not convinced then it, as so much else in 5e, is up to his or her judgement.

Answer 3

Sage Advice is that, as the "must" in the description implies, the spell consumes the target's movement. It is irresistible. The target can decide to use its action to make a save, or to do something else (such as attack with disadvantage). If it saves, it has no movement left that turn.

Answer 4

Unless specified otherwise, you can decide in what order to use your move, your action, and your bonus action. Otto's Irresistible Dance doesn't say that you use your entire move at the start of your turn, just that you must use your entire move dancing. Taking the action before your move becomes relevant means that you can end the spell right there, meaning your move hasn't been relevant yet.

This is all my interpretation of the rules, and how it would work in games I DM.

From the other answer, it seems this isn't entirely clear, and I have reached out to Jeremy Crawford on twitter for an answer. I will update this answer once he replies.