The AD&D 1e darkness spell description states that its area of effect is a 1 1/2" radius globe that can targeted on a spot up to 1"/level of the caster (PHB 69). Usually this is no problem to adjudicate, but I'm likely going to be dealing with a situation soon in which the spell is cast on a boat. Clearly, any moving boat/ship will clear the AoE in a matter of seconds (15 yards is nothing even at moderate speeds), so is the spell completely useless in this situation? Or does the darkness move with the boat/ship as it travels (the way it moves with the rotation of the planet in typical circumstances)? It seems to come down to whether the boat is a location or an object moving through a location.

I'm fairly certain this isn't covered in any of the core books (I checked the DMG notes on spells), so if there is an "official" answer, it's likely something from an issue of Dragon magazine. Does anyone know of such an answer? If not, does anyone have an opinion about how this should be ruled based on logic, rule of cool, or anything else (including subsequent editions)?


This is muddled in the text and therefore up to the DM, since matters of metaphysics are in the realm of the DM's world-building and -management responsibilities.

The spell doesn't say that it can be cast on an object, but that's a reasonable ruling for the DM to make, based on the way the light and darkness spells reference each other and drawing analogies between them. (The reasoning would be something like "M-U's light references cleric's light, which is cast on something specific, cleric's light is reversible to create darkness, M-U's light and darkness are just the 'straight' and reversed versions of cleric's light as separate spells...") The connections references aren't consistent or rigidly defined (e.g., M-U darkness doesn't reference anything), so such a conclusion isn't required for a DM to make, but it's a reasonable one, and something that the game gives the DM license to interpret appropriately for their own "milieu."

Nothing breaks either way that a DM rules, but it should be consistent as the fine details will eventually matter and be leveraged: if darkness is cast on a point in space, that allows for uses that aren't possible if it must be cast on an object (such as having a sphere of darkness hanging in the middle of a room, or having more control over where its boundaries fall by adjusting its centre point in space); while having it necessarily cast on an object as light must be allows it to be portable.

If you're the DM, no problem: make the ruling that makes sense. If you're a player strategising, ask your DM about this.

  • \$\begingroup\$ I am the DM for the game, so the decision is mine to make. My problem is that, in the particular situation that will likely to arise soon, it favors the PCs for the darkness to move with the object. Previously, the spell has been cast at a spot in a room, but that situation was inconclusive since the same effect could have been achieved if the reality was that the spell centered on the ground in the center of the AoE. The ship example, though, is going to be conclusive one way or the other and I'm not sure what precedent I want. \$\endgroup\$ – Craddoke Dec 12 '14 at 18:09
  • \$\begingroup\$ I mean, I kind of like the potential for mayhem if it's cast on a kobold who goes blundering about the battlefield throwing random people into darkness. On the other hand, that makes the spell much more powerful since enemies couldn't necessarily leave the AoE. Would there need to be a saving throw as with the offensive use of a cleric's light spell? \$\endgroup\$ – Craddoke Dec 12 '14 at 18:11
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    \$\begingroup\$ @Craddoke You can always rule that creatures are a special case and only inanimate & unattended (not held/worn) objects are valid targets. The spells definitely don't account for targetting creatures, as they lack all the saving-throw infrastructure that would normally be present. You could add such, but making them attach to mobile objects doesn't require making them also target creatures. \$\endgroup\$ – SevenSidedDie Dec 12 '14 at 18:14
  • \$\begingroup\$ Alright, that would solve my particular problem. [Edit: Scratch that next bit I wrote -- unattended objects is what you said; not as fun, but probably more balanced]. \$\endgroup\$ – Craddoke Dec 12 '14 at 18:17
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    \$\begingroup\$ @Craddoke You could make the spells able to target a spot hanging in space or an object. Make it caster's choice each time they're cast, and you'll retain verisimilitude without retcons and allow the spell to be useful in more situations. \$\endgroup\$ – gatherer818 Dec 12 '14 at 20:25

When casting a spell it moves with the world you are on, so why not a ship, or a wagon?

I believe that magic in game has some sort of physical properties with it. If you were to cast wall of fire on the ship, the wall would move with the ship because it is attached (and burning) on the ship. Light, and Darkness have magical properties that allow it to be bound to the world in a physical sense, allowing them to move with the object they are cast upon.

Since the material components are a bit of bat fur and a a pitch of coal, this is what makes the spell physical (in my opinion).

Now, granted, this is just what I think. From what I understand, there are no strict rules about this. I would say go with what you feel is right, and either allow it or not.

  • \$\begingroup\$ I'm kind of favoring a similar rationale -- that is why I mentioned the rotation of a planet not throwing off the location of the spell when cast on solid ground (although that would be a nasty surprise to include in a specific milieu). \$\endgroup\$ – Craddoke Dec 12 '14 at 18:15
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    \$\begingroup\$ Many D&D worlds, especially in older versions of the game, don't rotate. I don't think it's enough of them to say "most", but some are flat. Also note in later editions spells like light and darkness can be cast on objects to anchor them to the object, which has many useful applications; notably, it can be anchored to a vehicle or a piece of gear to cause it to move with that vehicle or character. \$\endgroup\$ – gatherer818 Dec 12 '14 at 20:22

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