Can a creature stop trying to pass through a Prismatic Wall or take a pause?

Question

If a player says they want to either step through the wall, charge through the wall or even put their hand through the wall, can they stop after the first (Red) layer's saving throw and pull back or do all of the effects happen on the same turn?

The Prismatic Wall spell states the wall is 1 inch thick, meaning each layer is around 0.143 inches or 0.363 cm thick. That leaves very little room for cautious entry.

What exactly happens when a player, who doesn't know anything about the wall, states they want to either try putting their hand through, or even charge through the wall.

The spell does say:

When a creature attempts to reach into or pass through the wall, it does so one layer at a time through all the wall's layers.

Is this enough leeway to allow the player to stop attempting to pass after the first saving throw of the Red layer? Can they pause and continue on their next turn? Or does it force the player to breach all the layers in one turn?

It seems all the saving throws, except for the Indigo layer, happen all at once, during the first turn they try to pass. So the creature trying to pass has very limited options on Actions, Bonus Actions, and Reactions they can use to pass the wall.

Considering the thickness of the wall it would require incredible reflexes to stop the movement.

Answer 1

You have to deal with all the layers

As you cite:

When a creature attempts to reach into or pass through the wall, it does so one layer at a time through all the wall's layers.

If you try to pass through, you will do so through all the layers. The "one layer at a time" explains how they are processed, that is you first deal with red, then orange, yellow and so on.

It may be that one of the earlier layers kills you — in that case you are not a creature any more for the later layers, but an object (a corpse) and will not be affected by them anymore.

Answer 2

The effects can all happen on the same turn: the spell says nothing about requiring an extended period to get through the wall. Nor does it require any actions.

A creature charging the wall has no chance of stopping itself during that one inch of movement, its only hope is to dodge the worst of the effects as it goes through.

Consider a more cautious adventurer trying to reach through. The character touches the wall and must make a dexterity saving throw to halve the fire damage. Any dex save involves movement of some kind, so it might involve pushing their hand further in, but could equally mean snatching it back. In a similar sitation, someone trying to unlock a door who triggers a trap will probably jump away if they succeed on a dex save, and not continue lockpicking uninterrupted.

Personally, if I were GMing this, I would say "you touch the wall, and feel an agonising burning as red flames engulf your hand. What do you do?" The outcome might be, for example:

• "I push quickly through the flames." Save for half fire damage, and continue to the orange layer.
• "I pull my hand back." Roll the save, but no further effect.
• "I ignore the pain." Stoically auto-fail the save, and proceed to the acid.

So yes, it makes sense that a creature can stop trying to reach through the wall. Taking a pause would be possible, but unwise. The earlier layers have not been discharged, so will continue to burn, corrode and so on. As long as a creature is continuing to reach through the wall, it should continue to suffer, on its turn, the effects of all the layers it has penetrated so far.