I'm about to start a campaign where my character (Tiefling / Druid) is traveling in disguise. My question is can I use the cantrip 'thaumaturgy' over and over again to disguise my eyes? The cantrip only lasts for a minute so I need to know if I can just keep on casting it indefinitely, or is there some sort of cool down period in between uses, or energy drain?

  • \$\begingroup\$ How would that play out in a social setting though? \$\endgroup\$
    – biziclop
    Feb 2 at 13:01
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    \$\begingroup\$ May not be an effective disguise as you will need to chant the spells invocation \$\endgroup\$ Feb 2 at 13:04
  • \$\begingroup\$ Welcome to the stack Rosemary! Take the tour when you have a moment, and feel free to peruse the help center for more in-depth info about the site. \$\endgroup\$
    – Jack
    Feb 4 at 15:13

2 Answers 2


The short answer is you can cast it as often as you like, but people will know you’re doing it because you have to say the magic words of the spell out loud, at least once every minute. And spellcasting isn’t secret - in fact it's usually very obvious, especially to others who can do it. On top of that, thaumaturgy is a spell designed to attract attention in various ways, so as written it’s probably not a good use for disguises.

But you can probably work out a specific loophole or alternative solution with your Dungeon Master (DM) to allow it, and I’ve suggested some options below as well. I’d also recommend checking in with the whole group (maybe via the DM) about the theme of having to hide who you are, which could be uncomfortably real for some folks.

You can cast a cantrip as often as you like

Cantrips are defined in Chapter 10 of the Basic Rules in the “Spell Slots” section (emphasis mine):

A cantrip is a spell that can be cast at will, without using a spell slot and without being prepared in advance. Repeated practice has fixed the spell in the caster's mind and infused the caster with the magic needed to produce the effect over and over.

So cantrips are explicitly spells you can cast as often as you want. There’s no energy drain or cool down. As long as you can perform the actions required to cast a cantrip, you can cast it. However, those requirements might be a problem, because...

People will probably notice

Casting a spell is not an instant effect that happens without any effort. To cast a spell, you must fulfil its requirements, which are mainly:

  • Spending the time required to cast it - for most cantrips this is an action, which is roughly 6 seconds (or at least it takes enough concentration that it limits what else you can do for around 6 seconds).
  • Providing the components for the spell - these can be verbal (speaking magic words out loud), somatic (making magical gestures with at least one hand) or material (producing specific ingredients, and/or using a magical tool like a wand or staff).

For thaumaturgy, the casting time is an action, so this limits how often you can cast it - once every 6 seconds, or ten times a minute. It lasts for a minute though, so that’s no big deal.

The real problem is that it has a verbal component. While you don’t have to wave your hands around or strike your druid’s staff on the ground, you do have to speak the magic words of the spell out loud. Doing that once every minute while in company is sure to attract some attention. Plus, unless otherwise specified, people can normally tell if you’re casting a spell, even if they don’t know what spell it is. This is made clear under “Perceiving a Caster at Work" in Chapter 2 of Xanathar’s Guide to Everything, in the Spellcasting section:

To be perceptible, the casting of a spell must involve a verbal, somatic, or material component.

Thaumaturgy involves a verbal component, which means it’s perceptible. So anyone who knows about magic could recognise you’re casting a spell, and according to the rules in that section of Xanathar’s Guide, they might even be able to work out what spell you’re casting.

How to hide your Tiefling eyes

Being able to hide a distinctive feature (which I’m guessing is for good reasons, not just for aesthetics) indefinitely is a pretty strong narrative effect for a cantrip, especially the extra one all Tieflings get for free. But it’s not game-breaking, especially if you put a bit of effort in to think about how to “balance” it, or make sure it doesn’t give you any kind of unfair advantage. That’s assuming balance is important for your game group! The limitations are important for the game, but they shouldn’t get in the way of you having fun.

The most important question to ask yourself about the concept is whether you want the disguise to be basically foolproof, so you don’t need to worry about it until it’s time for a dramatic reveal; or if part of the fun you want to have is the danger of being discovered, and having to come up with clever ways to get away with it. The suggestions below cover both scenarios.

On this note, though, it's important to check in about the whole concept with the other players, preferably during session zero - maybe through your DM, who is hopefully having these conversations anyway. This is because having to hide part of who you are to exist in the world is quite likely to interact with folks’ real world problems and even triggers. The rest of this answer assumes you’ve done that and this isn’t a problem in your group, but something you’re all on board with including.

Here are the suggestions for how to make this work:

  • Come up with a special rule for your character’s use of thaumaturgy with your DM. This is a perfectly fine thing to do, if it’s okay with them, but I’d advise making it a very specific special case that doesn’t give you other benefits. For example, perhaps you cast thaumaturgy speaking aloud for its other effects, but for changing your eye colour you have practiced long and hard to be able to cast it by muttering quietly under your breath, making it much harder (but not impossible) to catch you doing it.

  • Use a different spell designed for disguise. Thaumaturgy is designed to attract attention, so it’s not surprising it’s not entirely suited to this use. But the spell disguise self is designed to do exactly this kind of thing, and lasts for an hour without requiring concentration. (That doesn’t fix everything - disguise self still has verbal and somatic components - but it may be easier to hide casting a spell just once an hour.) It’s not normally available to druids, but you could ask your DM if your character could know it instead of one of the spells they’d normally prepare; that seems a pretty fair trade-off to me, even though disguise self can also let you disguise your whole body in quite flexible ways. Alternatively you could have a minor magic item that lets you cast it using your spell slots - a ring or a pendant, perhaps. Or there’s the official, uncommon magic item the Hat of Disguise (thanks RisingZan in the comments). The Hat lets you cast disguise self at will without needing a spell slot, much like a cantrip! That helps, but note it requires attunement (you can only attune three magic items at a once), and you have to be wearing it to use it.

  • You could also design together a specific custom minor magic item which doesn’t do anything except disguise your eyes; the magical equivalent of contact lenses! They might just work all the time, and have cost you something to get, to make it fair to they other players; or perhaps they could have some fun magical requirement, like needing to be taken off and cleaned in a dew drop at midnight every night. Or your DM might like the idea and let everyone start with one very minor, similarly specific use magic item.

  • Finally, as Darth Pseudonym pointed out in the comments, your character could wear dark or tinted spectacles. But that might not work for you narratively, depending on whether that’s something your campaign world has, the nature of your eyes (e.g. if they glow brightly), and your take on druid and/or Tiefling customs.

Whatever you consider, do talk to your DM. If this is an important part of your character concept, you can work something out! Your DM might be happy to handwave any rules-based limitations and ignore things like not being able to cast the spell before you first wake up, etc. I have done this with a warlock in my game with the Mask of Many Faces invocation that allows at will casting of disguise self, which she uses to maintain an entirely false physical appearance. The way we play it, there’s only a danger of her disguise wearing off at narratively interesting moments, so the character doesn’t have to be worried about being discovered in her sleep every night.

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    \$\begingroup\$ Or you could just wear dark glasses. It works for Crowley. \$\endgroup\$ Feb 2 at 20:10
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    \$\begingroup\$ @DarthPseudonym ha! And Mizu in Blue Eye Samurai. But that assumes the game world has spectacles in it, not a given, but it’s a good point. \$\endgroup\$ Feb 2 at 20:49
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    \$\begingroup\$ Good answer in general, but I specifically like the mention of the custom magic item, since in some games, trivial magic might be quite common. \$\endgroup\$
    – Jack
    Feb 4 at 15:16
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    \$\begingroup\$ Giving a character a Hat of Disguise for free isn't game breaking, as it's a fairly minor effect, and takes an attunement slot. It would still require recasting Disguise Self through the hat every hour though - the disguise is always going to wear off while sleeping, or if you're forced to take the hat off. \$\endgroup\$
    – RisingZan
    Feb 4 at 15:50
  • \$\begingroup\$ @RisingZan - I’d forgotten the Hat of Disguise! Good shout. And of course Warlocks can take an invocation to let them cast Disguise Self at will, though it also wears off after an hour. Thanks for the prompt, I’ll update the answer. \$\endgroup\$ Feb 4 at 23:13

You could do that, yes.

Basic rules, emphasis mine.

A cantrip is a spell that can be cast at will, without using a spell slot and without being prepared in advance. Repeated practice has fixed the spell in the caster's mind and infused the caster with the magic needed to produce the effect over and over. A cantrip's spell level is 0.


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