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Morgenstern Revisited: Improved & Greater Arcane Lock

Cover image for Morgenstern's Spellbook

For our first foray into revising the Morgenstern Family Papers, we’ll take a look at improved & greater arcane lock from Morgenstern’s Spellbook. I was going to talk about the spells babble and bat’s hearing, too, but the post got kind of long, so I think I’ll release those next week.

Arcane Lock

Arcane lock is a spell that allows the caster to make a door, portal, or container incredibly difficult to bypass or open. It dates back at least to first edition AD&D as wizard lock. In 3.5 edition, arcane lock allowed the caster to freely bypass its effects. The spell was permanent unless someone cast dispel magic on it, though it could be temporarily suppressed with a knock spell. Mechanically speaking, it increased the DC to break down the door by 10. With a wooden door being around DC20 to break, an intruder would need a ridiculously high strength (>30) to have any chance of breaking it down. But that didn’t stop ol’ Rasmus from “improving” the spell. I mean, there are definitely monsters out there with incredible strength. A wizard’s gotta protect themself, right?

So in Morgenstern’s Spellbook we find the spells improved arcane lock and greater arcane lock which behave the same except they increase that break DC by 15 or 20. Obviously, this was a design play on Rasmus’ need to tweak and improve existing spells, but it was also a send up of other spell progressions in 3.5e, like “lesser restoration“, “restoration“, “greater restoration“. They didn’t show up a lot, but they were frequent enough to make me wonder why there weren’t more. I like how 5e implements higher level casting improvements right inside the spell descriptions, now. Though, you can still find a few lesser→greater chains.

On to Fifth Edition

For fifth edition, arcane lock is essentially the same as 3.5e, with the addition of being able to assign friendlies who can pass through it or to set a password. And now the +10 to DC applies not only to breaking the door/container but to picking any locks on the object. I don’t think successfully picking said lock would actually get you through the door, since the spell works on even portals that don’t already have locks. But, I digress.

In revising improved and greater arcane lock for 5e, I didn’t want to go far with the DC increase, since 5e characters can have no more than a 20 Strength score. Sure, there are still the strong monsters, but I wanted to ground things a bit from Rasmus’ flights of fancy.

The guidelines for how hard it is to break down a door are a little looser for 5e, with the GM just sort of going for the right feel regardless of the composition of the door. I imagine a typical dungeon door would be Easy (DC10) to Medium (DC15) difficulty. Arcane lock already takes an Easy door to Hard (DC20) and a Medium door to Very Hard (DC25). For a typical “strong” character just starting out at level 1, their Strength bonus will be around 3, maybe 4 if they’ve done some racial min-maxing. So, they’ll have only a 20–25% chance to break down an Easy door. Zero chance for a Very Hard door. Even as levels increase, at most that Strength bonus will be 5, giving the strong character only a 5% chance to break the Very Hard door.

Final Polish

As you can see, any improvements to arcane lock in the DC department have diminishing returns. It didn’t make sense to have two new arcane lock spells. So, I’ll be going with one spell called master arcane lock (with a nod to the classic padlock maker) that adds 15 to the break/pick DC rather than 10. But there is another aspect of arcane lock that we can address, which is you can just chop through the dang door. Given the AC and HP guidelines for objects in 5e, that would take only 2–3 rounds for our stereotypical wooden dungeon door. So, master arcane lock also gives the door, portal, or container resistance to bludgeoning, slashing, or piercing damage. That should slow down those pesky adventurers long enough for the evil wizard to escape.

Honestly, if I were doing arcane lock from scratch, I would just add some “higher level casting” text to the end of the entry to add these new effects when cast at 4th level. I’ll probably houserule that into my further games, as it’s a bit more elegant and saves the wizard from having to hunt down a new spell to write in their little book. I’d also give it the ritual descriptor.

Master Arcane Lock

4th level abjuration (ritual) [wizard]
Casting Time: 1 action
Range: Touch
Components: V, S, M (gold dust worth 100 gp)
Duration: Until Dispelled

As arcane lock except:

  • Knock has no effect on master arcane lock. Master knock suppresses master arcane lock for 10 minutes with a successful Charisma save.
  • The DC to break the door, portal, or container increases by 15 and the object is resistant to bludgeoning, piercing, or slashing damage.