The arcane lock spell says that a closed door, window, gate, chest, or other entryway "becomes locked". The spell says

it is impassable until it is broken or the spell is dispelled

Okay, impassable is pretty clear, but it's last part of the spell description that confuses me:

the DC to break it or pick any locks on [the object] increases by 10.

Again, the break part is clear: the locked object is off limits unless you can break it with an increased DC. But where does pick any locks fit in? Is the implication that if the door or chest is locked, picking that lock at the increased DC will defeat arcane lock? What if the chest wasn't previously locked? And, if this applies when the chest has a lock but not otherwise, what about the addition of a lock makes it possibly easier to defeat than otherwise? If the object wasn't previously locked, can it now be picked with a DC of 10 (increased from the previous DC of 0)?

Or, is it that one can pick any locks at an increased DC, but the object is still impassable? If so, what is the point of raising the DC? A kind of wizards' ha ha to the rogues out there?

  • \$\begingroup\$ If I missed anything when you revise your question could you shoot me a pint? \$\endgroup\$ – wax eagle Aug 30 '14 at 21:09
  • \$\begingroup\$ @waxeagle Maybe? :) Looks like you're unclear on the same part that's confusing to me. \$\endgroup\$ – mattdm Sep 2 '14 at 23:58

Any normal means by which you'd open a door or window or break an object. It's just harder to do so (though just picking the lock may not be enough).

The last line of this spell handles this

While affected by this spell, the object is more difficult to break or force open; the DC to break it or pick any locks on it increases by 10. (PHB 215)

So if the DC to force open a locked window or door is normally 10, then one under the effect of Arcane Lock is now 20 (and so on and so forth).

Basically, the effect of this spell is to make an easy check a hard one, a medium check a very hard one, and a hard check nearly impossible.

As far as the text "impassible", it seems to mean in this context that the door/window can't be opened by normal means except with the higher DC. It's unclear to me whether or not picking a lock has any effect on this text, though it seems quite clear that forcing the door open is in bounds. I would definitely rule that at the very least picking the lock(s) on the door would ease the DC to force it open (As you're only dealing with the magic and not any physical locks).

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    \$\begingroup\$ On the last bit: is there a rule somewhere for increased DC for forcing things open when there is a lock involved? If not, would you houserule that anyway? Otherwise, your ruling doesn't make much sense to me, as it makes it easier to get through doors with locks (have rogue pick lock, then barbarian smash with reduced DC...) \$\endgroup\$ – mattdm Sep 2 '14 at 23:59
  • \$\begingroup\$ @mattdm unfortunately, rules like that are DMG material. Generally though, I would rule that a locked door is DC 10-15 to force open, and an otherwise unlocked door is DC 0. (a barred door being DC10-15, barred and locked DC 15-20 to force). Thus an increase in both the lock pick DC (From 10-15 -> 10-25) and open DC (0->10 or 15->25) makes sense. With picking the lock reducing the DC of forcing the door to 10/20. \$\endgroup\$ – wax eagle Sep 3 '14 at 0:16
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    \$\begingroup\$ Since this answer predates the release of the DMG which is now available, does it need to be updated? \$\endgroup\$ – Dyndrilliac Aug 18 '15 at 17:58
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    \$\begingroup\$ Historical Note: In earlier editions of D&D, you could not use lockpicking to open an arcane lock. Generally we had to find another way around, or hack the door apart with a "universal axess key." (Oh, and the axess key didn't work on doors made of iron or stone; we'd just wreck the blade if we tried.) \$\endgroup\$ – GMJoe Jan 19 '19 at 21:24

I know this is an old question, but I had the same question. I've also tried to construct an answer that makes sense. This is what I've gotten from Arcane Lock.

The spell says:

....[the entryway] is impassable until it is broken or the spell is dispelled or suppressed.

The spell later states that the DC to break the entryway or pick any locks on it increases by 10. But why would it increase the DC to pick locks if it is impassable until broken, dispelled, or suppressed? My theory: in case the character attempting to open the entryway doesn't know Arcane Lock is in effect.

If you don't know Arcane Lock is in effect, you would likely try to pick the lock. At that point, you may find the lock to be exceptionally difficult to pick. Depending on the player, they could then make the assumption that the lock will require a key, or an Arcane Lock is in effect. But unlocking a lock doesn't make the entryway any easier to get past. It's just there to make the entryway seem like it could be as difficult as it is due to mundane means.

  • \$\begingroup\$ So, if the rogue does make that high DC, they still can't get through? \$\endgroup\$ – mattdm Jul 21 '18 at 20:18
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    \$\begingroup\$ That'd be my ruling. The lock may be harder, but the lock isn't what's keeping the entryway closed. The spell is. It'd be like saying the door requires a specialized key, and thus can't be picked. \$\endgroup\$ – Iter Jul 21 '18 at 20:26

Funny thing that has happened in some games Ive been in, we just remove the door. While an entrance may be locked by magical means, nothing protects the joints or area surrounding where the door or window is any greater than normal.

If you have the time, patience and tools you can unhinge a door or otherwise remove parts around it so the door can remain locked but not do its job at preventing entry. Its low tech and mundane but it works.

  • \$\begingroup\$ I don't think this would work with Arcane Lock. It seems pretty clear that it seals the door/window, not just allowing a lock to be more difficult to open. \$\endgroup\$ – Jason K Nov 13 '14 at 17:47
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    \$\begingroup\$ It explicitly states that the door/lock/window is affected. The spell does not affect the area or wall surrounding, just the portal the door/lock/window occupies. The spell is not sentient and thus unable to adapt to player tactics to circumvent. Now...it might be easier to burst through in comparison to the time it might take to remove the whole of the area around the opening but that's a completely separate matter. \$\endgroup\$ – TechImp Nov 14 '14 at 19:46
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    \$\begingroup\$ If the GM gives you unlimited time, the campaign is usually an easy one. There are other higher-level solutions as well, obviously spells like transmute rock to mud, assuming the wall around the door is made of stone. You could also use an adamantine tool or weapon to carve it out much more quickly than with mundane tools. The problem is that they are very costly in one of time, gear quality, or spell level required just to deal with a level 2 spell. I think that stacking the odds in your favor to deal with the increased break/lockpick DC is a more practical mundane solution. \$\endgroup\$ – Lucas Leblanc Aug 18 '15 at 18:29
  • \$\begingroup\$ I like this answer but perhaps you could expand a little? What rules did you use to do so? (Checks, tools, etc...) Do you think this would work with every door? \$\endgroup\$ – Jason_c_o Jul 22 '18 at 1:23

I would rule successful pick lock opens the door.

For me it looks like the last part of spell description states two ways to break or force the door open, those are: break or pick lock. It also states that if the door has many locks, the spell protects them all.

It would also sound strange, that so much effort is used to tell how the spell affects picking, and then successful pick would not open the door.

So on base of these assumptions, I would rule door with no lock to be DC 10 to open, if locked with arcane lock.

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    \$\begingroup\$ Are you proposing a DC of 10 to pick the lock on a door that doesn't have a lock? How do you even do that? \$\endgroup\$ – Mark Wells Jan 18 '19 at 23:33
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