Turn duration in 0e context

23 May, 2026

One of the first things you notice when starting to play 0e is that the vast majority of spells state their duration in "turns". While later editions had already solidified the terminology and distinction between rounds and turns, 0e uses the term "turn" quite loosely, with a floating meaning across different contexts: from 1-minute melee turns, through 10-minute dungeon movement turns, to 1-day-long wilderness travel turns. While we can most certainly dismiss the latter, having spells like Infravision (duration: 1 day), Web (duration: 8 game hours), and Suggestion (duration: 1 game week), the question of whether a given spell lasts mere minutes or hours is very important.

So, let's dig in.

Contents

• Comparative Table
• Greyhawk Spells
• Quotes and Clues
• The Conclusion
• Further Reading

Comparative Table ↩

The first instinct is to compare the spells with "turn" duration to their counterparts in Chainmail, Swords & Spells wargame, and AD&D 1e. Granted, 1e is an entirely different system, but it cannot be dismissed entirely either, being a direct descendant of 0e. At least, we could see if there's some logic or system present. Plus, for the other sources, the "turn" term is defined much more clearly:

• Chainmail: 1 turn = 1 minute
• Swords & Spells: 1 turn = 2 minutes*
• AD&D 1e: 1 turn = 10 minutes, 1 round = 1 minute

* Despite having 2-minute turns, the S&S Spell Chart corresponds with the 0e duration in turns, except the following spells (not counting those with the "full game" duration):

Abbreviations:

• R — round
• T — turn
• L — level
• conc. — concentration
• perm. — permanent
• M — Magic-User
• C — Cleric
• D — Druid

Sources:

• CM — Chainmail¹
• 0e — Original D&D²
• GH — Supplement I: Greyhawk³
• EW — Supplement III: Eldritch Wizardry⁴
• S&S — Swords & Spells⁵
• 1e — Advanced D&D 1e⁶

As you can see, most of the spells with 0e-turn duration became spells with 1e-round duration. This, however, does not help us much, because there's still a good amount of spells that became 1e-turn duration. What is interesting, none of these are "combat" spells, and all of these can be classified into the following rough categories:

• Exploration:
  • Detect Evil (½-turn/level)
  • Detect Invisible (½-turn/level)
  • Find the Path
  • Find Traps
• Illumination:
  • Darkness (mix of turns and rounds)
  • Light
• Protection:
  • Anti-Animal Shell
  • Anti-Magic Shell
  • Anti-Plant Shell
  • Prot. from Evil, 10' Radius (C)
  • Prot. from Normal Missiles
  • Rope Trick
  • Shield (½-turn/level)
• Transformation:
  • Polymorph Self
  • Shape Change
• Transportation/Passage:
  • Fly
  • Levitate
  • Lower Water
  • Part Water
  • Plant Door
  • Water Breathing
• Weather Control:
  • Control Temperature
  • Control Winds

Also, this is not even a hard rule, with the following spells breaking the pattern:

• Exploration:
  • Detect Magic
  • Locate Object
• Protection:
  • Obscurement (just barely, being almost ½-turn/level)
  • Prot. from Evil

Still, taking the spell durations from the 1e is a cheap shot. The original game should clearly be playable by itself, not referencing the following edition released years later.

We need to dig deeper.

Greyhawk Spells ↩

The Greyhawk³ supplement is an interesting case, its spells distinguishing between "turns", "melee turns", and even "game hours/days/weeks". Moreover, some spells that were given round-duration in 1e have the "turn" duration here, disproving the assumed distinction between "turn" and "melee turn":

• Animate Objects
• Blade Barrier
• Conjure Animals
• Earthquake
• Ice Storm
• Mirror Image
• Power Word Stun
• Repulsion
• Ventriloquism

Also, there are a couple of peculiar durations that alternate between "movement" and "melee" turns:

• Fear: "Duration: 6 turns (movement or melee as applicable)."
• Snake Charm: "Duration: 7–12 melee turns or 2–5 turns."
• Delayed Blast Fire Ball (not duration, but delay in this particular case):
  • GH: delay 10 melee turns (or 1 movement turn)
  • S&S: delay 1 turn
  • 1e: delay up to 5 rounds

So, in case of Fear, the duration apparently switches tenfold "as applicable", Snake Charm doesn't even explain when you should use the 7–12 vs. 20–50 minute duration (1e clarifies this distinction as in-combat vs. out-of-combat casting), and Delayed Blast Fire Ball supports the formula of 10 melee turns = 1 movement turn.

The Detect Magic spell, initially being a "short duration" spell (alongside Read Magic and Read Languages in Men & Magic), was given a "2 turns" duration in Greyhawk (misspelled as "Direct Magic" here). Its original wording includes "The spell is of short duration (one or two readings being the usual limit)." Since the scrolls are analogous to spells for Magic-Users, these "two readings" are necessarily equated to "2 turns" with the implication of them being "melee turns", one spell or scroll being possible to activate per turn of combat. But why then is it "turns" and not "melee turns" in Greyhawk?

Quotes and Clues ↩

Furthermore, I've gathered a couple of additional quotes pertinent to this topic.

A mention of the evolution of the term "turn" → "melee turn" → "melee round" → "round" to distinguish it from the "movement turn":

All of the fantastic people and monsters were discussed in terms of CHAINMAIL. Spell ranges and areas of effect were scaled to CHAINMAIL. Saving throws were devised to match the combat abilities of creatures, which were in turn meshed with the troop types normally included in CHAINMAIL. As D&D grew from CHAINMAIL, it too used the same scale assumptions as its basis. Changes had to be made, however, in order to meet the 1:1 figure ratio and the underground setting. Movement was adjusted to a period ten times longer than a CHAINMAIL turn of 1 minute, as exploring and mapping in an underground dungeon is slow work. Combat, however, stayed at the CHAINMAIL norm and was renamed a melee round or simply round.

— D&D Ground and Spell Area Scale, Dragon Magazine #15, pp. 13–14.⁷

A reminder of one [movement] turn containing 10 melee rounds:

Further, any creature or person that looks at it has the same chance (5%) per round, of becoming hypnotized. Again, the effect is cumulative. For instance, looking at it for four melee rounds means that the looker has a 20% chance of becoming hypnotized, and subject to the commands of the wearer. When it is used in a non-combat situation, where turns are longer (remember, one turn contains 10 melee rounds), there is a 20% base chance of becoming hypnotized, with an additional 5% per turn increase. Any magic user that becomes hypnotized by the robe who has an intelligence of 17 or 18 has a 10% or 20% chance, respectively, of going permanently insane.

— Robe of Scintillating Color, The Strategic Review Vol.1 No.5, p.7.⁸

Trolls' description uses the "melee round" and "turn" interchangeably:

[...] Trolls are able to regenerate, so that beginning the third melee round after one is hit it will begin to repair itself. Regeneration is at the rate of 3 hit points per turn.

Compare this with the "draft version",⁹ which supports the point of "melee round" being a later evolution of game terminology:

Regeneration begins on the third turn of melee, and it proceeds at 3 points per turn thereafter.

The Eldritch Wizardry⁴ supplement sometimes gives specifying statements in the psionic abilities descriptions (only SOME of them though!):

• Precognition: "[...] anything beyond 30 turns (five hours) becomes a high difficulty precognition;"
• Body Control: "As a rule of thumb assume that the individual is able to withstand the equivalent of one die of damage from the substance or surroundings for one (ten-minute) turn."

Curiously, the Molecular Agitation ability implies the 1-minute melee turns instead:

[...] if this agitation is continued for ten turns the following effects will be noted:

[...]

flesh: blistering*

metal: hot to touch**

[...]

* each turn thereafter the creature will take 1 point damage, cumulative (1, 2, 3, 4, etc.) if the ability continues to be used against him.

** thereafter becomes searing hot as the heat metal spell of druids and will cool at the same rate if the attention of the psionically endowed person leaves the item.

The Conclusion ↩

Based on the presented material, I can suggest three approaches that allow for the most logical ruling on turn durations in 0e.

Appeal to the Future

When checked against the Advanced edition, in most of the cases we can assume that non-combat spells last for movement turns, while all others last for melee turns.

However, I don't like this reasoning, because it requires referencing another and released much later game's rules.

Spell Purpose

This one requires the referee to discern if the spell is primarily used in combat or not, then applying the "melee" and "movement" turn duration respectively.

This also works, but puts a heavy load on the referee's rulings about which effect constitutes a combat usage and which does not.

Relative Turns

Turn is turn of whichever mode the game is currently operating on — melee turns in combat, and movement turns in the dungeon.

After all, why not? The combat is a chaotic environment that overwhelms the casters with various distractions, and targets of their spells are also more aware and wary of charms and spells being cast on them (just like we see in the Robe of Scintillating Color).

Thus, just like Snake Charm lasts longer on calm snakes than agitated ones, and Fear lasts for melee turns instead of movement ones in combat, we can assert that Water Breathing cast in combat lasts for 12 melee turns (12 minutes) instead of 12 movement turns (2 hours) when cast while exploring the underwater caverns.

This approach raises other questions:

• Will the spell cast before combat expire faster if the magic-user engages in combat during its duration?
• Will the spell cast in combat last longer if it ended before the spell?

While both versions are usable, I would argue that using the turn length of the mode the spell was cast on is more coherent to the in-game verisimilitude, since once the spell is uttered, the caster isn't required to actively maintain it (except the "concentration" spells, which require it explicitly). Thus, a shortened duration of combat-cast spells can be explained by the haste and erratic surroundings in which the caster had uttered it, opposed by the calm and collected approach of casting the spell outside of combat.

And finally, this approach gives us a reliable and objective rule:

Unless stated otherwise, assume 1-minute melee turns for the spells cast in combat, and 10-minute movement turns for the spells cast outside of combat.

Further Reading ↩

While I was researching the topic, I stumbled upon some relevant musings and discussions:

• Delta's D&D Hotspot: Spells Through The Ages – Duration
• Delta's D&D Hotspot: Spells Through The Ages — Durations Redux
• ODD74 forums: Spell Duration Turns
• Solo Dungeon Crawler: OD&D Spell Duration - How long is a turn?

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