The knock spell says (emphasis ine):

A target that is held shut by a mundane lock or that is stuck or barred becomes unlocked, unstuck, or unbarred. If the object has multiple locks, only one of them is unlocked.

If you choose a target that is held shut with arcane lock, that spell is suppressed for 10 minutes, during which time the target can be opened and shut normally.

When read separately, it is clear that knock only unlocks one lock each time, and knock suppresses arcane lock cast on the target.

However, what happens if the target has both a mundane lock and is locked with arcane lock?

  • Do both of them get unlocked?
  • Or perhaps because arcane lock counts as a lock, does it only unlock either the mundane or the arcane lock (not both)?

3 Answers 3


Both effects happen

Both effects are independent. If you cast arcane lock on something, it does get locked magically, there is no need for it to even have a physical lock, for example, windows normally have no locks:

You touch a closed door, window, gate, chest, or other entryway, and it becomes locked for the duration. [...] it is impassable until it is broken or the spell is dispelled or suppressed. Casting knock on the object suppresses arcane lock for 10 minutes.

Arcane lock itself is a spell effect, not an actual lock, in spite of the name - names are suggestive, they can help interpretation, but are not functional. It does not say it creates a lock, it says the object becomes "locked" so that "it is impassable until it is broken or the spell is dispelled or suppressed". Because arcane lock is not actually a lock that could be unlocked, it does not count against your number of locks.

If you happen to lock the same target using normal locks and arcane lock, and cast knock on it, then arcane lock gets suppressed, and one of the normal locks gets unlocked.

  • 9
    \$\begingroup\$ This has absolutely changed how I understand arcane lock. \$\endgroup\$
    – SeriousBri
    Commented Jan 15 at 13:11

You can, obviously, rule that it does both, and the effects are separate. However, this would be contrary to historical versions of the spell. Potentially, it even makes the spell more powerful in some ways than previous editions, whereas it is otherwise weaker.

In 2nd and 3rd edition, knock bypassed two means of preventing you from opening the door, and wizard/arcane locks were included in this number. The purpose of the extra text about arcane locks was that knock only suppresses them for 10 minutes, and doesn't outright remove them or disable them indefinitely like you might otherwise expect.

So, for instance, there are published modules (e.g. Rary the Traitor) where doors are triple locked and double wizard locked, requiring three knock spells to bypass a single door. Alternately, you can realize that teamwork (or multiclassing) is better, by using one (required) knock for the wizard locks, while a thief handles the physical locks.

So, if you rule that knock disables all the arcane locks on a door as an additional effect, you are making it more powerful than previous editions in that respect. In the special case of a door that is single locked and single arcane locked, it is as powerful as previous editions. Since the intention of limiting it to one lock in 5e is presumably to make it less powerful, be aware of that.

  • 5
    \$\begingroup\$ While the comparison to prior editions is interesting, I don't think it is sufficient to measure balance. A lot changed between 2nd/3rd and 5th editions, in terms of numbers, balance, and adventure design (I'm not very broadly read, but in the modules I have seen I have not seen multiple locks on a door being a feature). \$\endgroup\$
    – BBeast
    Commented Jan 16 at 1:39
  • \$\begingroup\$ That may be. I hadn't thought about it until I read the module I mentioned. But it seems (to me) like one in a list of many examples where people complain about, 'balance,' but don't read or use relevant aspects that are already in the game (or interpret them to be irrelevant). My (real) front door has two locks on it, and it's not a particularly high security situation. US hotel rooms often have three locks (or rather, two locks and a 'bar' of sorts). If you're worried about knock stealing rogues' thunder, lock your stuff up like Rary does. \$\endgroup\$
    – Dan Doel
    Commented Jan 16 at 16:23
  • 1
    \$\begingroup\$ Note that in 5e, you can't "double arcane lock" a door, thanks to the rules on spell stacking. This means that a single casting of Knock will never suppress multiple Arcane Lock spells. So it seems that this is consistent with the historical precedent, since Arcane Lock can unlock/suppress at most two means of locking something (one mundane and one arcane). \$\endgroup\$ Commented Jan 16 at 17:01
  • \$\begingroup\$ @BBeast There is a door locked with 9 hidden locks in Dungeon of the Mad Mage (p. 133), so there is published precedent for multiple locks even in 5e. \$\endgroup\$ Commented Jan 16 at 17:15
  • \$\begingroup\$ @NobodytheHobgoblin I stand corrected, then. I suppose knock specifies it unlocks just one lock, after all, so attaching multiple physical locks makes sense. (Ryan's point about only one arcane lock making sense in 5e reinforces (with a more concrete example) my general point about the differences in design, though.) \$\endgroup\$
    – BBeast
    Commented Jan 18 at 0:42

A lock is something that keeps a portal locked

An effect, device, mechanism or similar that causes something to be locked and keeps it locked something is a lock. Knock bypasses 1 mechanism that is keeping the door locked.

Arcane Lock keeps the door locked. When you cast Knock, it is suppressed for 10 minutes.

A physical lock may also be keeping the door locked. If your door is kept locked by 2 things, Knock disables or bypasses only one of them.

So you get to disable 1 lock.

You can read it another way

You could read the 2nd paragraph as completely independent of the first paragraph, and treat "arcane lock" which makes a door "locked" as not a lock. English is ambiguous.

Talk to your DM

Whenever wording is at all ambiguous, your first resort should be to speak to your DM. As a DM, consider how you want it to work -- both are reasonable. It is clear that Knock is simple to defeat by layering on a pile of simple locks, so having Arcane Lock require an extra casting of Knock or not isn't a huge power bump either way.


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