[RPG] n official source for the properties of stone

armor-classdamage-resistancednd-5ehit-pointsobjects

The issue comes up mainly in relation to the spell wall of stone, which states that:

A nonmagical wall of solid stone springs into existence at a point you
choose within range. […] The wall is an object made of stone that
can be damaged and thus breached. (PHB 287)

The wall is a nonmagical object from the moment it is created. This, to me, reinforces that it is ordinary stone, with all the properties of it. However, the spell unhelpfully neglects to inform us of many of its properties, in particular any damage threshold, resistances and immunities.

Objects are immune to poison and psychic damage. You might decide that
some damage types are more effective against a particular object or
substance than others. […] Big objects such as castle walls often
have extra resilience represented by a damage threshold. (DMG 247)

While we can make up our own ruling, I am interested whether we got any official information that can be applied here.

Is there any officially published material that describes the properties of stone, especially a wall and its resistances, immunities and damage threshold? If yes, what does it say? Bonus points if that wall was created by the spell wall of stone.

Best Answer

Stats for stone are not collated anywhere, but you can piece some useful things together...

  1. Stone is mentioned explicitly a few times in the DMG section on objects:

In contrast to the spell description, which says the created wall will have an AC of 15, the AC for stone is given as 17. This disrepency could possibly be explained away by size -larger targets are considered to be easier to hit and so normally have lower AC, and the wall the the spell creates is pretty big (ten x 10 ft. by 10 ft. panels).

Use common sense when determining a character’s success at damaging an object. Can a fighter cut through a section of a stone wall with a sword? No, the sword is likely to break before the wall does.

You might decide that some damage types are more effective against a particular object or substance than others. [...] bludgeoning damage works well for smashing things but not for cutting through rope or leather. [...] A pick can chip away stone but can’t effectively cut down a tree. As always, use your best judgment.

I know 'use your best judgment' is not the takeaway you're looking for here but I'd apply these directions to give stone resistance against piercing and slashing damage but not bludgeoning. As you quoted 'objects are immune to poison and psychic damage' but I'd also give stone immunity to necrotic damage and resistance to things like fire and acid damage. How you apply your judgement is obviously up to you - so I won't list every damage type here.

  1. The guidelines on HP don't tally that well with the spell description:

A stone wall is normally considered Resilient and (at least) and each panel (at 10 ft by 10 ft) is large in size so would heave atleast 27 or 5d10 hp. The 30 hp per inch of thickness quoted in the spell description, seems at first glance to be within this range but the spell actually allows for 180 hp per panel, when you take the full thickness of a six inch wall into account.

  1. You can draw on damage thresholds from published modules

The DMG doesn't provide explicit guidelines on appropriate damage thresholds. However, other published supplements do provide damage thresholds can be refferred to as a point of comparison:

  • The hulls of larger boats in Ghosts of Saltmarsh (and now available via the Basic Rules) have damage thresholds of between 10-20
  • A submarine in Waterdeep: Dragon Heist has a damage threshold of 15, while it gives steel doors a threshold of 10
  • Infernal machines and chains in Baldur's Gate: Descent into Avernus all have a threshold of 10.
  • In Tomb of Annihilation there's a Crystal Window with a damage threshold of 15 and more chains with a threshold of 10.

With all of the above in mind, a damage threshold of 15-20 feels appropriate for stone.

As well as concerns of game balance and verisimilitude, when setting the damage threshold you might also want to consider exactly how difficult you want destroying the stone to be for your players, based on the current level. At low levels a threshold of 10 might be sufficient to impress upon your players the difficulty of destroying a wall, without completely removing the possibility of them doing so.

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