What happens if a vampire tries to enter a residence without an invitation?

Question

A vampire "can't" enter a residence without an invitation.

Forbiddance: The vampire can't enter a residence without an invitation from one of the occupants.

Source : Monster Manual, p. 297.

There's been some discussion (e.g. here and here) about just what constitutes a valid "invitation", but not on what happens if the vampire lacks a required invitation but decides to try anyway.

What happens if a vampire tries to enter a residence without a valid invitation? To be clear, I'm not asking for clarification on what a residence is, what an invitation must consist of, or exactly who qualifies as a resident eligible to issue an invitation, but about what happens when the vampire truly lacks a required invitation.

• Does this work as a mental block on the vampire, so they cannot even attempt to enter (e.g. their brain essentially "shuts down" or their body refuses to take action that would violate the prohibition)?
• Does the vampire encounter some sort of magical or physical barrier at the threshold of the residence (e.g. some sort of forcefield)?
• Can the vampire physically enter, but they experience some sort of punishment (e.g. taking damage, receiving instant death, being teleported away, being slapped with a fish, etc.) for having transgressed the rules?

In other words, is the prohibition more like a Star Wars-style droid restraining bolt (where the subject is literally being mind-controlled into being unable to perform the prohibited action), or is it more like a social skill where vampires know that while they can physically enter a residence without an invitation, it is just not something that vampires do and offenders are subject to social ostracism or being hunted down by the Fellowship of Vampires Code of Conduct Enforcement Patrol?

In response to a comment by Owen Reynolds, I'm not so much concerned about vampires being forcefully shoved into residences (as that case is covered in a linked question), but on what happens if the vampire proceeds to try to enter out of ignorance, stupidity, deceit, delusions of grandeur, etc. For example, if a PC tricks a vampire into believing they have permission to enter when they actually don't (e.g. "That is my house over there, you may enter." when in fact the house is owned by a hostile NPC and not actually occupied in any way by the PC), would the vampire instantly know that the permission is fake or would they find out when they attempt to step over the threshold? Would they successfully cross the threshold, but later experience a crisis of conscience when they find out later from a legitimate occupant that they unwittingly transgressed one of the foundational ethical rules of vampirehood?

Similarly, if I allow a PC to play a vampire and, one day, they see what they think is a guard tower but is actually the residence of a wizard hermit who has not in any way granted permission to the PC to enter, is there guidance on what I should tell the player or is it truly uncharted territory? E.g. do I say "For some reason you just know that entering that building is a bad idea and thinking about it fills you with dread. Is there anything else you would like to do here?", or would something like "You proudly approach the tower, but upon lifting your foot to cross the threshold, you are hit with a strong bolt of lightning which throws you five meters from the house. You take 2d6 lightning damage." be more appropriate?

Answer 1

They cannot enter

You've put in the relevant quotes in your answer, they simply can't enter and that's all the info that 5e has given us. With no details provided by source books, the DM is free to narrate with what works for the story they are telling.

A DM can add whatever narrative they'd like around that, but mechanically it's simple: they can't go in.

Answer 2

It could be any of them, depending on what the DM prefers, but Vampires would certainly know this, either instinctively, from remembering the legends they knew in human life or by being trained by other more experienced vampires.

The first two of your possible examples are functionally the same thing - whether their body refuses to enter or the dwelling refuses to let them enter is mostly mechanical flavor that produces the exact same result. It's the third option where things get interesting, they can physically enter if they tried, but with consequences so drastic they won't do it. In this case it'd likely be death for the vampire - the only consequence that truly makes violating the rule never worth doing. Some mystical/holy force that disintegrates destroys them when they cross a threshold, they burst into flames with no realistic chance of putting them out before they died, etc.

It's not likely to be simply social convention, punished by the "Fellowship of Vampires Code of Conduct Enforcement Patrol" because that would rarely actually prevent much of anything - you run into the territory of "It's not a crime if you kill all the witnesses" there.

As always the rules should serve the story and the GM, not the other way around (I know not everyone agrees here). So any of these options work, even lesser options like losing all their powers. Mechanically the reason should be whatever fits the story and setting best - however in some of these cases the players should be told in advance by their GM, since anyone growing up in a world where vampires are a clear and present threat would probably know they need invitations to enter, and have a general idea of what happens if they try without it.

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Edit to answer added question on PC vampires:

That's really up to you like the rest of it - though I would suggest leaning more towards the "barrier" option if you want to allow vampire PCs. If it were just a little damage when they cross the threshold, then powerful vampires would still do it and shrug off the hit (2d6 maxes out at 8% of Strahd's hp for example) so this doesn't really fit the rules. If it were guaranteed death that can ruin the game for the player who's character ends up dying by walking through a door.

If it's a barrier however then it opens up interesting story opportunities if the PC is hiding their nature. If they know instinctively that the building counts as a dwelling, they have to roleplay their way out of being expected to walk into buildings with the party (or roleplay their way into proper invitations). If they don't have any way of knowing what counts as a dwelling until they try, then the doorway not letting them through reveals their vampire nature and they have to roleplay their way out of that.

Answer 3

Vampires are probably aware of their limitations.

We probably don't need to reflect on what would happen if a vampire tried, because it's quite likely that a vampire would be aware of their limitations and would not even try. For example, the vampire Strahd often brings along minions when he goes gallivanting about Barovia:

Whenever Strahd appears in a location other than his tomb or the place indicated by the card reading, roll a d20 and consult the Strahd’s Minions table to determine what creatures he brings with him, if any.

If Strahd encounters the party in a residence, it is stated:

If the characters are in a residence, Strahd’s creatures break through doors and windows to reach them, or crawl up through the earth, or swoop down the chimney.

Strahd is perfectly aware that he cannot enter a residence without an invitation, so rather than try, he brings along creatures that can.

Now Strahd is a supremely intelligent vampire (20 Int), but even the most lowly vampires, vampire spawn, aren't stupid, having an Intelligence score of 11 (equivalent to that of the average human). So we wouldn't expect even a vampire spawn to try to enter a residence without an invitation and wonder why it isn't working.

Answer 4

As others have pointed out, they simply cannot enter, and the game does not give more details than that. It is up to the DM to determine what that looks like. I am a fan of buffy and angel, so I'd probably have it work like in those shows. The vampire tries to enter they simply cannot, as if there was a forcefield preventing entry. Even in those shows it doesn't specify whether it is a mental block or a physical one, but either way you can see them struggle to try to move forward but they simply cannot. No where in the books does it mention damage or being flung backwards, they just can't go forward

Answer 5

The way I see it, they would know it instinctively. There's nothing listed in any official books about it, so I guess that means it's up to the discretion of the dungeon master. Either a barrier or actual damage could work nicely as a consequence/enactment of this rule.