[RPG] What happens when you cast the Disguise Self spell again while currently under its effects


Let's say you are a human warlock with the Mask of Many Faces invocation. You cast disguise self and alter your form to that of an elf. While under the effect of this first illusion (before it expires), you cast it again to change your form to a dragonborn. What happens?

Do you go from elf > dragonborn? Do you temporarily revert to your base human form?

Best Answer

You don’t revert to your original form, but beyond that it’s up to the DM

The rules for Combining Magical Effects (PHB pg 205) come into play here:

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.

For example, if two clerics cast bless on the same target, that character gains the spell's benefit only once; he or she doesn't get to roll two bonus dice.

So what is important here is to determine which effect is the most “potent”.

There is no clear guidance in the rules on how to determine potency when two spells have the same effect. There are some reasonable options in this case:

  1. If the spells have the same effect, the one with the longest remaining duration is most potent (think a sorcerer who has used their extended spell meta magic to double the duration of the first casting)
  2. The spell cast last is the most potent
  3. The first spell effect remains the most potent until it ends, at which point the second effect takes over.

My ruling from the games I DM is that the players can choose when they cast the second spell if they want to use either #1 or #2, but only if they are casting it on an ally. If they are casting the spell on an enemy I apply #2.

In your case these two options are functionally equivalent, so you would look like an Elf that turned into a Dragonborn.