Last Updated: 191115
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 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 the effect of 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 for surprise (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.
“Surprise” indicates 1 segment of surprise; “Complete Surprise” is defined as 2 (or more) segments of surprise [c.f. , DMG-Crossbow of Speed], OR as 4 segments of surprise (c.f., PHB-Aerial Servant spell). 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).
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) 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, 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 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.
- The Dexterity Reaction/Attacking Bonus affects that many segments of surprise for that individual only and only if lightly or unencumbered [reaction normal or better, PHB p. 101], 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 them during a Surprise segment, the attack is deferred to the standard initiative round (DMG, p. 62).
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.
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.).
- 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.
- Move Silently 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 their stealth and ability to be hidden. If they have opened 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) due to their stealth. This definition doesn’t explicitly include conditions, but rangers can’t surprise opponents aware of their companions and thus includes same distance requirement as elves and halflings—rangers must be at least 90’ in advance. 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 familiar terrain (e.g. surprised on 1-4 in d6 instead of 1-2 in d6), due to their ability to hide in known terrain. This definition doesn’t define other required conditions, but barbarians can’t surprise opponents aware of their companions and thus includes same range requirement as elves, halflings, and rangers—they must be at least 90’ in advance. Armor is not a factor for barbarians.
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. The elf rolls a 2, and the orc rolls a 4. The Elf is surprised for 2 segments, the orc for 4. For the first two segments they stare at each other, after which time the elf has 2 segments (the maximum) to act before beginning standard initiative.
In the example above, if the elf had a Dexterity of 17 and only lightly encumbered, the elf would reduce the number of segments it was surprised by 2, and (except that I limit the number of actions to 2) would have all 4 segments to act.
For any segment that both parties are surprised, nothing happens. 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).
- Move 1” (and potentially close for melee).
- Prepare (i.e., drawing or setting a weapon).
- Melee or grapple (if prepared and within 1”).
- Charge 1” (if close enough) and attack.
- Fire a missile weapon, if prepared and ready. No Attacking Dex Bonus (PHB, 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).
- Roll on the Assassination Table (if an assassin).
- Strike from the rear at +4 to hit instead of the standard rear attack bonus of +2 (if, of course, at the rear). Striking from the rear also negates any shield or dexterity bonus.
- Strike from the rear with damage multiplier for back stab (if thief or assassin and, of course, from behind) with the above +4 bonus. 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. However, they can’t gain surprise, so have only the standard rear attack.
- Spells that require but a single segment to cast are possible to use 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.
- If not surprised, a party with Surprise could withdraw (where possible) unnoticed. For me, that requires Complete 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).
- A thief back stabbing from Move Silently triggers a Surprise roll, with a minimum of 1 segment of surprise for the opponent.
- An attack when using Dust of Disappearance is always by surprise (assuming for the entire party). 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.
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.
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.