Inspired by Does an Enlarge/Reduce spell on a druid affect the beast form if the druid Wild-Shapes?

Focusing on the specific effect of the Enlarge/Reduce spell:

You cause a creature or an object you can see within range to grow larger or smaller for the duration.

Consider a human who is, for reasons which will become obvious, named Inflatoman.

Inflatoman is the target of an Enlarge spell cast by Engorgo. He grows to twice his size becoming a large creature.

While the Engorgo maintains concentration; Reducto hits Inflatoman with a reduce spell, which clearly causes him to revert to his original size. While these spells have not cancelled each other, their effects have.

So, what happens:

  1. if Engorgo stops concentrating while Reducto keeps concentrating:

    1. Inflatoman stays his normal size; Reducto's spell has already done all the reducing it can do.
    2. Inflatoman shrinks to small size; with Engorgo's spell removed the effect of Reducto's reasserts itself.
  2. if Reducto stops concentrating while Engorgo keeps concentrating:

    1. Inflatoman stays his normal size; Engorgo's spell has already done all the enlarging it can do.
    2. Inflatoman grows to large size; with Reducto's spell removed the effect of Engorgo's reasserts itself.

An alternative way of asking this is: Is the growth from an Enlarge spell a one shot effect that causes the target to grow at the beginning and then shrink at the end OR a continuous effect that is trying to make the subject be twice the size they would otherwise be? Vice versa for Reduce.

  • \$\begingroup\$ Another possibility is that Reducto's spell causes Inflatoman to shrink to a small size (i.e. it both undoes the Enlarge effect, and reduces the target in size). \$\endgroup\$ – Lexible Jun 4 '15 at 19:45

From the Player's Handbook (p. 205) and the Player's Basic Rules (p. 81):

The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however. Instead, the most potent effect--such as the highest bonus--from those castings applies while their durations overlap.

This rule can lead to a couple of different rulings:

  • The DM could rule that the first casting of the spell Enlarge/Reduce (ie. Engorgo's casting), being the first casting, doesn't get combined with the second (Reducto's) casting, resulting in a Large-sized Inflatoman.
  • The DM could also rule that the first casting is more potent (because it was cast first), to the same result.
  • The DM could ALSO rule that the second casting is more potent (because it will last later) and overrides the first casting, resulting in a Small-sized Inflatoman.
  • Finally, the DM could houserule that the Enlarge and Reduce effects are two different spells, and therefore cancel each other out.

TL;DR: It's up to the DM.


Given that the spells require concentration, they are an ongoing effect. When the caster's concentration ends, the ongoing effect ends.

To compare against your alternative, let's look at what happens:

  1. The spell is an ongoing effect that lasts while concentrating.
    • Caster casts spell. Target's size is changed.
    • Caster stops concentrating. Ongoing effect ends, returning target to normal.
  2. The spell is an instantaneous effect.
    • Caster casts spell. Target's size is changed.
    • Caster stops concentrating. A secondary instantaneous effect is triggered, returning target to normal.
  • \$\begingroup\$ Though, having a look at the linked question, I don't think you continue to grow later if there wasn't enough room when it was initially cast. It's restrained by the initial circumstances, then maintained for the duration of concentration. \$\endgroup\$ – Adeptus Jun 4 '15 at 3:37

When the spell ends (for whatever reason), their effect ends too. Enlarging a creature makes it grow when the spell is cast, and shrink when the spell ends.

From this, we can conclude that, no matter your interpretation of whether the spell is maintaining a certain size for the creature or not, when Engorgo stops concentrating on his spell, Inflatoman shrinks one size category, and when Reducto stops concentrating on his spell, Inflatoman will grow one size category.


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