I’m Surprised

Oops, I’m Surprised (1st Edition AD&D)

Last updated: 190613, … 210211

I abandoned using Surprise years ago—so long ago I don’t specifically remember why. I suspect because I tried to make the rules make sense, and as written they don’t (and can’t, there are errors in the early printings of the PHB and DMG!). The rules are also surprisingly (hah!) unclear on who rolls for what effect. Am I rolling for whether I’m surprising or surprised? What if the result is modified more than once?

 I’ve recently been inspired to dig into some of the more fiddly AD&D rules, and have been impressed at how well those rules work once I understand them, so I thought I’d try Surprise again. That said, I’ve modified the below just a bit to be consistent with the rest of my house rules (see Initiative). I also limit surprise to a single attack per segment, without stacking, to a maximum of 2 segments. That’s intentional, otherwise 7th level Elven Ranger catching someone completely flat-footed could gain 10 melee attacks during Surprise (and more extreme examples exist!)

A surprised party is one caught unawares or unprepared. In such circumstances the non-surprised (or less surprised) party has an advantage reflected by free segments of actions against the surprised party prior to rolling initiative. It is possible for both parties to be surprised equally—with Surprise thus having no effect.  Parties are unaware of how surprised the other side is.

Prior detection negates the possibility of being surprised. Light can spoil the possibility of surprise for one party. Noise can negate surprise considerations, whether the sound is the normal progress of the party or a fruitless attempt to open a door. A party hearing something at a door negates their possibility of surprise. Magical devices can possibly negate surprise by detection of thoughts or intentions. In all such cases, only parties subject to surprise roll to determine surprise (DMG, p.62). If one party is making considerable noise which is discernible by the other party, the latter will have the options of fleeing or concealment regardless of Surprise; the former negating the encounter, the latter allowing distance to be 1″ to 4″ before discovery by the noisy party (DMG, p. 62).

For each side, if the chance of surprise exists, a single d6 is rolled to determine whether their entire side is surprised. By default, on 1 or 2 their side is surprised, for the number of segments equal to the number rolled on the die, otherwise (on 3-6) they are not surprised.

If both parties roll results in their range for Surprise, Surprise is calculated based on the net of the two results: “Assume A [surprised on 5 in 6] rolls a 4, so it is surprised for 4 segments unless B rolls a 1, in which case A party’s inactive period will be only 3 segments, or if B rolls a 2, in which case surprise will last for only 2 segments (4–1 = 3, 4–2 = 2).” DMG, p. 62.

If a creature surprises on 4 in 6, it can surprise for up to 4 segments (when their opponent rolls 1-4 on a d6). “Surprise” indicates 1 segment of surprise; “Complete Surprise” is defined as 2 (or more) segments of surprise [c.f. , MM-Catoblepas, DMG-Crossbow of Speed, PHB-Phantasmal Killer, UA-garrote, MM2-Dracolisk, G2/G3, and the potential f4 segments of surprise for the Aerial Servant(PHB/MM), Eldrich Wizardry for origins]. The Boalisk prompts “Complete Surprise” on a 1-2; whether the Boalisk rolls a 1 or 2, it will surprise for 2 segments.

Once Surprise is completely resolved, both parties roll Initiative.

Encounter Range

If either or both parties are surprised, the distance will typically be 1″ to 3″, as surprise is normally a factor only in close encounter situations. When outdoors or otherwise appropriate, the distance (6d4″ DMG or d6+4″ PHB/DMG) is reduced (or increased) by 1″ for each segment of surprise (DMG, p. 49). Distance is also modified by terrain type:

Scrub  -1 per distance die on all 3’s and 4’s.
Forest  -1 per distance die on all numbers (00’s are possible).
Marsh  -1 per distance die on all 2’s 3’s, and 4’s.


Modifiers to the Chance of Being Surprised (Your Die)

A party (or group of monsters) is surprised only as easily as its most perceptive member if that awareness can be communicated; e.g., in a party with a ranger (surprised only on 1 in 6), the entire party is only surprised on a 1. If awareness is limited (such as a human ranger in the dark), special class or race benefits do not apply (WSG, p. 60).

  • Rangers (& Duelists) are surprised only on 1 in 6 (decreasing the surprise range by 1 [Polyhedron #12]), normally to 1 in d6 instead of 1-2 in d6) due to their alertness.
  • Barbarians are surprised only on 1 in 10 (decreasing the normal range by 4 from 2 in d6 to 1 in d10 (see Calculating Cumulative Surprise below) due to their alertness. This further decreases the normal range by an additional 2 (to 1 in 20) if in familiar terrain. I find this overpowering at a party level, and instead consider the Barbarian ability as identical to the Ranger ability.
  • The monk’s chance of being surprised drops 2% per level, thus a 5th level monk reduces the range to be surprised by 1 (only 1 in d6) due to their alertness.
  • With a proficiency check, characters with Alertness are surprised only on 1 in d6 (decreasing the range by 1, normally to 1 in d6 instead of 1-2 in d6). This does not stack with other class abilities—those classes effectively have this proficiency without the requirement for a proficiency check. Assuming an ability to communicate to others in the party, their chance of being surprised is also reduced by that amount.

Modifiers to the Chance of Surprising Others (Their Die)

A party with an increased chance to surprise their opponents increases their opponents’ range from 1-2 in d6 to 1-3 or more (also increasing the potential number of segments that their opponent(s) can be surprised), but only if that increased chance of surprise is true for the entire party (e.g., all rangers, a group of only halflings and elves 90’ in advance not wearing armor, all huge spiders, etc.).

  • Using lights can negate the possibility of surprise for one party.
  • Noise can negate surprise considerations, whether the sound is the normal progress of the party or a failed attempt to open a door.
  • Invisibility increases the opponents’ chance of being surprised by 1 (increasing the opponents’ range by 1, e.g. surprised on 1-3 in d6 instead of 1-2 in d6) due to being hidden.
  • Hiding in Shadows increases the opponents’ chance of being surprised by 1 (increasing the opponents range by 1, e.g. surprised on 1-3 in d6 instead of 1-2 in d6) due to being hidden. One cannot Hide in Shadows and Move Silently.
  • Move Silently/Silence increases the opponents’ chance of being surprised by 1 (increasing the opponents’ range by 1, e.g. surprised on 1-3 in d6 instead of 1-2 in d6) due to stealth. One cannot Hide in Shadows and Move Silently.
  • Elves and Halflings surprise opponents 1-4 in d6 when not in metal armor and 90’ in advance (increasing their opponents’ range by 2, e.g. surprised on 1-4 in d6 instead of 1-2 in d6), due to both their stealth and ability to be hidden. If they open a portal, that chance for surprise returns to 1-2 in d6.
  • Rangers surprise opponents 50% of the time (increasing their opponent’s chance of being surprised by 1, e.g. surprised on 1-3 in d6 instead of 1-2 in d6 [Polyhedron #12]) due to their stealth. This definition doesn’t explicitly include conditions, but rangers can’t surprise opponents aware of their companions and thus require the same distance as elves and halflings—rangers must be at least 90’ in advance. Metal armor however is not a factor for rangers.
  • Barbarians increase their opponents’ chance of being surprised by 1 (increasing their opponents range by 1, e.g. surprised on 1-3 in d6 instead of 1-2 in d6) due to their stealth, with an additional 1-point increase if also in familiar terrain (e.g. surprised on 1-4 in d6 instead of 1-2 in d6), due to the barbarian’s ability to hide in known terrain. The barbarian’s definition doesn’t define other required conditions, but barbarians can’t surprise opponents aware of their companions and thus require the same distance as elves, halflings, and rangers—they must be at least 90’ in advance. Metal armor is not a factor for barbarians when calculating Surprise.


Modifiers are cumulative when dissimilar. Example: A lone invisible elf not wearing metal armor comes upon an orc. The standard chance of being surprised is 1-2 in d6. For the orc, its range is increased due to the elf (+2), but not further increased due to the elf’s invisibility (+1); the orc will be surprised if it rolls 1-4 in d6.

If both parties roll results in their range for Surprise, Surprise is calculated based on the net of the two results. For any segment that both parties are surprised, nothing happens. The elf rolls a 2, and the orc rolls a 4. The elf is surprised for 2 segments, the orc for 4 segments. For the first two segments they stare at each other (both still surprised), after which time the elf has 2 segments of Surprise to act before rolling standard initiative.

If an attacker with Surprise attacks an opponent who for whatever reason is not surprised (e.g., a Dexterity bonus), the attack is ineffective.

While the attacker’s opponent(s) is/are surprised, but the attacker is not, the attacker may:

  • Do nothing.
  • Attempt to parlay.
  • Evasion is automatic if outdoors (PHB, p. 69) or Complete Surprise.
  • Move 1″ (and potentially close for melee).
  • Prepare (i.e., drawing or setting a weapon).
  • Charge 2” (if close enough) and attack.
  • Fire a missile weapon, if prepared and ready. No Attacking Dex Bonus (DMG, p. 64).
  • Use a breath weapon (if normally possible!).
  • Attempt to activate a magical device. The device could activate during surprise. If not enough surprise segments exist to complete activation, subtract 2 for each surprise segment from the future initiative roll.
  • Hide in Shadows (if thief, assassin, or monk).
  • Melee or grapple (if prepared and within 1″).
  • Back stab (if thief or assassin and within 1″). Surprise is required to gain the damage multiplier and +4 to hit (instead of the standard +2 for a rear attack) (DMG, p.74)2. If at the rear, strike at +4 to hit for each surprise segment. Striking from the rear also negates any shield or Dexterity bonus. The back stab damage multiplier (DMG, p. 74) applies for only the first surprise attack [Polyhedron #31].

After surprise ends, if a thief removes themself from melee such that their opponents are no longer aware of the thief’s presence, the thief could reenter combat, attempt to Move Silently behind their opponent, and back stab again. However, they can’t gain surprise as long as their opponent is aware of their location, so have only the standard rear attack bonus of +2 with no damage multiplier.

  • Roll on the Assassination Table (if an assassin and within 1″).
  • Spells that require but a single segment can be cast in a surprise segment. Other, longer casting time spells can only be begun during surprise (DMG, p. 61), and if not completed subtract 1 segment (2 under my 20 segment initiative system) for each surprise segment from the future initiative round. Regardless of Surprise duration, only one spell can be cast during Surprise.

Modifiers to the Duration of Surprise

The Dexterity Reaction/Attacking Bonus affects that many segments of surprise for that individual only, e.g. on a range of 1-2, with the group rolling a 2, a lightly-encumbered character with a 16 Dexterity (+1 Reaction/Attacking) would be surprised for one less segment. If an opponent attempts to attack the character during a Surprise segment, the attack defers to the standard initiative round (DMG, p. 62).

  • Only lightly or unencumbered characters [reaction normal or better, PHB p. 101] gain the Dexterity Reaction/Attacking Bonus:
    • All armors except leather and elfin chain are fairly bulky or bulky, making the character worse than lightly encumbered for purposes of Surprise.
    • Magic armor has the same encumbrance as non-magic armor. The properties of magic armor allow movement at the next higher base rate (DMG, p. 28), not with less encumbrance.
    • Large shields are bulky (see “Very Heavy” below). Magical shields however are non-bulky with respect to encumbrance (DMG, p. 28).
  • “Heavy” encumbrance (70# or fairly bulky armor/equipment) defines “no bonuses” to Surprise. The Ranger ability to adjust the Surprise roll? Gone!
  • “Very Heavy” encumbrance (#105 or bulky armor/equipment) causes a character’s reactions to be “slowed” (in a situation of surprise) (PHB, p.102). If the individual is surprised, they are surprised for an additional segment.
  • Encumbered (> 105# or very bulky equipment) characters are slowed greatly, which extends the duration of surprise by an additional 2 segments (when already surprised).

Individual adjustments never create (or negate) Surprise itself; instead they subtract (or add) segments for individuals once the party is surprised. If the Dexterity Reaction modifier reduces the Surprise segments for an individual, that individual still can’t act during Surprise even if Dexterity reduces the individual’s Surprise segments to 0.


I choose to limit surprise to 2 segments. To avoid high Dexterity players never being surprised, the total duration of Surprise must be calculated, including adjustment for Dexterity. Only then should the limit be applied.

Additional Interpretations

  • If not surprised, a party with Surprise could withdraw (where possible) unnoticed. For me, that requires Complete Surprise (more than 1 segment of surprise).
  • Move Silently must normally be checked before a Surprise roll; Move Silently affects the Surprise roll, and the Surprise results determine encounter distance. Alternately, the thief can attempt to Move Silently for a single segment of Surprise.
  • A thief Moving Silently can prompt a Surprise roll even when expected.
  • A thief failing to Move Silently triggers a Surprise roll for both sides (as the thief doesn’t know they failed their Move Silently).
  • When combining the elven/halfling/ranger ability to improve the chance of surprise move silently with the thief Move Silently, the thief will add an additional 1 to the surprise roll if the thief is moving at the exploration rate (12’/round).
  • While performing a back stab from Move Silently, the thief could be considered to also be invisible (as their opponent can’t see them), surprising on 1-4 in 6.
  • An attack when using Dust of Disappearance is always by surprise (assumed for the entire party if silent). Roll normal surprise, with a minimum of 1 segment of surprise for the opponent.
  • A character wearing the Robe of Eyes cannot be surprised.
  • The Crossbow of Speed can fire on the 2nd segment of complete surprise.
  • Sandstorms and frostbite both increase the chance to be surprised by 1 (increasing the party’s potential surprise range by 1).
  • Assassins can don disguise to create the opportunity for surprise. There is only a 2% chance per day that the victim (or one of their henchmen) will notice the disguise. A combined total Wisdom and Intelligence above 20 increase that chance by 1% per point (PHB, p.29).
  • A garrote attack will only succeed with Surprise from behind.
  • If, at the beginning of a round, a new 3rd party suddenly enters combat, initiative pauses. Each engaged party makes a new surprise roll. Surprise is resolved, and then Initiative continues as normal.
  • Attacking a (normally) sleeping creature triggers a Surprise check (with a minimum of 1) as if the attacker is Invisible (1-3 in 6).
  • Priests of Nerull use the mechanic of “surprised 2 in 12” to represent the ability to be surprised on only 1 in 6, but still be surprised for two segments.1

Calculating Cumulative Surprise (Optional)

Any time the range of surprise for a group would be reduced to 0 (e.g. a 0 in 6 chance), the die size is incremented instead (next 1 in 8, then 1 in 10, etc.). A party with everyone lightly encumbered with a Dexterity of 17 (a +2 Reaction Adjustment) would therefore be surprised on 1 in 8. If the group also had a ranger, the chance of surprise would be 1 in 10. The same applies to a Surprise chance of 6 in 6, instead converting to 7 in 8, etc.

For a by-the-book example of a similar methodology, consider the greenhag, which surprises 5 in 6. If invisible (which normally would be 6 in 6), the greenhag instead surprises 19 in 20.

There are rare instances where surprise could be converted into d100. If the opponent uses a different die than d6 to calculate surprise (d8, d10, even d20), then modifications to their range of being surprised could be calculated on d100 (such as adding 16.67% from the ranger ability to the 5% chance of the creature surprised only 1 in 20). Instead, modify by the same number (applying the “1” from the 1 in 6 chance to the 1 in 20, making the range 2 in 20), because that’s faster, easier, and reflects the increased difficulty to surprise that creature.


TSR 2010, Players Handbook, 1978.
TSR 2011, Dungeon Masters Guide, 1979.
1Dragon Magazine, Issue 71, “Deities & Demigods of Greyhawk”, March 1983.
3Polyhedron #12, “Dispel Confusion”, 1983.
2Polyhedron #31, “Dispel Confusion”, 1987.


Author: Rick

A DM for *mumble* years, I've been playing AD&D since junior high. I've currently got two separate campaigns running, both in Mystara. I've been told when they handed out hobbies, I stood in the short lines. I actively cycle tour, kayak, play board games, read, develop home automation software, volunteer with the American Red Cross, and work on a never-ending stream of home repairs. In my wake I've left paintball, medieval full-contact combat (SCA), computer gaming, Heroclix, tablet weaving, and kite construction.

2 thoughts on “I’m Surprised”

  1. Very nice article. I can’t locate one reference:

    No Attacking Dex Bonus (PHB, p. 64)

    Curious where this came from.

    1. Wow, good catch! Thanks for your attention to detail. That reference should be DMG. p. 64 instead of PHB.
      “The Dexterity Attacking Adjustment is for missile firing considerations when initiative is considered.” Surprise is prior to considering Initiative.

      The PHB defines the RAT as “the penalty or bonus for both surprise (q.v.) situations and missile combat attacks. Translating that out a bit, the RAT is the modifier for the surprise roll. It’s also the adjustment for missile combat attacks that aren’t during Surprise. With its later publication date, the DMG should always win out over the PHB.

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