[RPG] Can the Remove Curse spell be cast on yourself?

If you are looking for an "in-game" resolution Ravenloft, and by extension Barovia, has always had a history of twisting things to its liking. The Demiplane of Dread is quasi-aware after all (or at least was in past editions). There is ample room for the environment to adapt to this advantage and thwart it, the walls can become more and more opaque over time to this ability as it adapts.

Another idea is that it could also change to start picking up "false positives". The ability could indicate the presence of things that are not actually there or at least not perceptible to the others but harmless. Like the spirit of a dead girl could set it off as she watches from the sidelines of a battle. He could freak out at "seeing" something more on the battlefield that can cause confusion and mishaps during combat.

I think that Zeiss Ikon has it right that you can just renege on the gift but I agree that an in game solution is usually best for flavor. Then your issue will be when/if they leave Barovia you will have to figure on a "fix" at that time. Or you can just say that the alterations by the Demiplane were fundamental and can't be reversed. Maybe the sensory overload was amplified by the Demiplane so that his brain can no longer process the input through solid objects?

These are not RAW solutions and simply based on flavor and experience over years of dealing with Ravenloft in books and modules. I personally would have limited that to 30ft, but that is my table not yours.

Your questions:

1. Can a character under the effects of Geas cast Remove Curse on herself? YES.

2. Can this be prevented by saying "Bring me 100gp from the offering plate every day and don't cast remove curse on yourself?" NO.

3. How does this work? SEE BELOW:

Question 1:

There is nothing in the spell description stating that the creature is magically compelled to do, or to not do, anything, even disobeying the command you have given. What there is is a consequence for disobeying, which it explicitly states is possible:

While the creature is charmed by you, it takes 5d10 psychic damage each time it acts in a manner directly counter to your instructions, but no more than once each day.

So YES they can cast Remove Curse on themselves. or in fact do anything else.

Question 2:

The geas spell description (PHB p.244) states that

You place a magical command on a creature that you can see within range, forcing it to carry out some service or refrain from some action or course of activity as you decide

This means that you can tell them to do something or tell them not to do something, but not both. Also it is singular, you can refer to only a single course of action. So you can't command them to not cast Remove Curse on themselves (or anything else) as well as the primary command.

So NO you can't prevent them from casting Remove curse on themselves in addition to the primary command.

Question 3:

I am going to rephrase the "How does this work?" question to something more specific: At what point does the target of a geas know it has had a geas cast on it?

The spell description states:

If the creature can understand you, it must succeed on a Wisdom saving throw or become charmed by you for the duration.

and that

A creature that can't understand you is unaffected by the spell.

This means that they have to hear and understand your verbal command to be able to follow it, there is no "telepathic" magical transference of meaning. This means the creature effected knows at least that someone has given it a command it can hear in a language it can understand at the time of casting. As stated earlier there is no magical compulsion to follow the command.

Do they know they have had a spell cast on them? The Rules answers 2016 state, using suggestion (PHB p.279) as an example, gives strong guidance:

You’re aware that a spell is affecting you if it has a perceptible effect or if its text says you’re aware of it (see PH, 204, under “Targets”). Most spells are obvious. For example, fireball burns you, cure wounds heals you, and command forces you to suddenly do something you didn’t intend. Certain spells are more subtle, yet you become aware of the spell at a time specified in the spell’s description. Charm person and detect thoughts are examples of such spells.

Some spells are so subtle that you might not know you were ever under their effects. A prime example of that sort of spell is suggestion. Assuming you failed to notice the spellcaster casting the spell, you might simply remember the caster saying, “The treasure you’re looking for isn’t here. Go look for it in the room at the top of the next tower.” You failed your saving throw, and off you went to the other tower, thinking it was your idea to go there.

Breaking this down you’re aware that a spell is affecting you if:

• it has a perceptible effect
• if its text says you’re aware of it at some point

You might miss that a spell is affecting you if:

• the spell is subtle
• you failed to notice the spellcaster casting the spell

Applying this to Geas:

• it does not have a perceptible effect at the point of casting and
• the description does not explicitly state you are aware of it.
• The damage done by the spell is psychic, in the mind of the target and that only happens at the point you go against the command and The spell has only a Verbal component, no handwaving or bits of fleece so it is subtle (a velvet wrapped hammer springs to mind)

So it is down to whether the character notices the spell being cast as to whether they know that a spell has been cast on them, up until they take damage and at that point it is whether they recognise the spell effect for what it is.

The PHB p203 describes a Verbal component of a spell as:

Most spells require the chanting of mystic words. The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion.

This means that the words of the command given are not the only part of the Verbal component, at the very least the words have to be said at a particular pitch and resonance etc. So it will be down to the DM to set the difficulty for the target, or any other witness, to notice and recognise that a spell has been cast.

The target has to be aware of the command so no perception roll is required so as a DM I personally would base it on an Int(Arcana) roll (or Wis(Arcana) if you, like I do, use the alternate rules on skill characteristics with a different take on the information provided by a success). I'd suggest a difficulty of around 13 depending on the circumstances.