D&D 5E How does Arcane Lock work exactly?

In a couple of games I've been playing, we have been using arcane lock as an offensive tool:

  • Rush in to a room(usually from a window or door way - hopefully getting surprise)
  • Cast arcane lock on a door (it could be the way we come in or it could be the door leading further into a place with more enemies)
  • Cast silence.

This has worked on several occasions, usually when we have a bit of planning, to pin in a boss and/or prevent enemies from escaping and warning others of our presence. (the silence nerfs our casters, obviously)

Other times, we cast it on doors as we explore, to give us an exit strategy: Move into a room, cast it on the door behind us. If we have to escape, only we can open the door easily. These strategies make it worth the 25gps it costs if we use it sparingly.


Then I read it a bit more closely. All it does is lock a door, allow designated people to open the door 'normally', and increase the dc to pick/break it.

If the door has a lock on it, it will automatically lock the door and increase the dc from (for example) 15 to 25.

BUT WAIT! if I'm a designated person, to open the door normally, do I not still need a key or be forced to pick the lock at DC 15(instead of 25)? Or does the door just automatically unlock for me without the need of a key?

Also, if I use a password, it just suppresses the effect of the spell. All suppressing the effect of locked Arcane Locked door is drop the DC from 25 to 15. It doesn't say it 'unlocks the door'.

IF it does allow you to bypass the lock without a key, why not just cast Arcane lock on a locked door and designate yourself as able to open it? Which renders Knock useless. My only answer to that is the lock must be unlocked when you cast the spell?
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the Incomparably Shrewd and Clever
I would say that the spell magically locks the door on top of any physical mechanisms on the door. If the door is physically locked as well, then yes, arcane lock will add to the difficulty of picking it (by non-designees), but you still need to be able to physically unlock it someway, even if you are a designated opener. Otherwise, if you encounter a physically locked door, you cast arcane lock on it and suddenly you can open it? That is stepping on the knock spell's toes too much, IMO, as well as being a bit illogical to cast a locking spell to open something.

Your tactical use of the spell is clever! As a limiting factor, there is the 25gp material component cost (as you mention), but a larger concern is that the spell's range is touch. You can always arcane lock the door you just came through, but if there is a door on the other side of the room, getting to it may be a problem...

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