How Sneak Attack Works in 5e

Sneak Attack adds extra d6s to one hit per turn: 1d6 at Rogue level 1, one more die every odd level, 10d6 at level 20. The hit must use a Finesse or a Ranged weapon, and you need either Advantage on the attack roll or an ally within 5 feet of the target (and no Disadvantage). It works once per turn, not once per round, so a hit on someone else's turn can trigger it again. Below: the rule quoted, the dice by level, the odds, and Cunning Strike.

The rule

The Rogue's level 1 feature:

Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack roll if you have Advantage on the roll and the attack uses a Finesse or a Ranged weapon. The extra damage's type is the same as the weapon's type.

And the second way in:

You don't need Advantage on the attack roll if at least one of your allies is within 5 feet of the target, the ally doesn't have the Incapacitated condition, and you don't have Disadvantage on the attack roll.

Four conditions, all on the attack:

• An attack roll. A spell that forces a save never qualifies. Neither does a spell attack: it uses no weapon.
• A Finesse or Ranged weapon. For example a Dagger, Rapier, Scimitar, Shortsword, Shortbow or Hand Crossbow. A Longsword never qualifies, even in a Rogue's hand.
• Advantage, or an ally beside the target. The ally must stand within 5 feet of the target, not of you, and must not be Incapacitated.
• A hit. It applies to "one creature you hit", so a miss never spends it.

Dice by level

The column comes from the SRD's Rogue Features table. It counts Rogue levels only: a Fighter 4 / Rogue 1 rolls 1d6.

What it does to a goblin

A level 1 Rogue, Dexterity 16, attacks at +5. The target: a Goblin Warrior, AC 15, 10 Hit Points. One attack, crits included (a Critical Hit rolls the Sneak Attack dice twice too):

One die more than doubles the chance to drop the goblin. Advantage does more again, because it lifts the hit chance as well. That is why Rogues hide: Cunning Action makes Hide a Bonus Action from level 2, and Steady Aim gives Advantage from level 3:

As a Bonus Action, you give yourself Advantage on your next attack roll on the current turn. You can use this feature only if you haven't moved during this turn, and after you use it, your Speed is 0 until the end of the current turn.

When Advantage and Disadvantage cancel

The ally route needs "you don't have Disadvantage." The SRD's rule on mixing them:

If circumstances cause a roll to have both Advantage and Disadvantage, the roll has neither of them, and you roll one d20.

So a Rogue shooting from hiding (Advantage) at long range (Disadvantage) has neither. With no Advantage, Sneak Attack needs the ally; with no Disadvantage, the ally route still works.

Once per turn, not once per round

The rule says "once per turn." Your turn is one; every other creature's turn is another. An Opportunity Attack uses your Reaction on the enemy's turn:

To make the Opportunity Attack, take a Reaction to make one melee attack with a weapon or an Unarmed Strike against the provoking creature.

If it hits with a Finesse weapon and the conditions hold, Sneak Attack lands again. A readied attack works the same way. Each costs your Reaction.

Cunning Strike, level 5

At level 5 a Rogue can trade Sneak Attack dice for an effect:

Each effect has a die cost, which is the number of Sneak Attack damage dice you must forgo to add the effect. You remove the die before rolling, and the effect occurs immediately after the attack's damage is dealt.

The save DC is 8 + Dexterity modifier + Proficiency Bonus. The three level 5 options:

• Poison (1d6). Constitution save or Poisoned for 1 minute, a new save at the end of each of its turns. You need a Poisoner's Kit on you.
• Trip (1d6). Large or smaller: Dexterity save or Prone.
• Withdraw (1d6). Move up to half your Speed after the attack without provoking Opportunity Attacks.

A level 5 Rogue with Dexterity 18 attacks at +7 with save DC 15. Against a Bandit Captain (AC 15, Dex save +5, Con save +2) and an Ogre (Dex −1, Con +3):

Each costs 3.5 damage. With an ally beside the target, a Rapier turn deals 13.1 on average against the Captain; with Trip, 10.65. Is a Prone target worth 2.45 damage? Prone says:

An attack roll against you has Advantage if the attacker is within 5 feet of you.

A Fighter at +5 beside a Prone Captain hits 79.75% of the time instead of 55%. One ally swing usually earns back more than the die you gave up, as long as the ally acts before the Captain stands up on its turn. Against the Ogre, Trip lands three times in four.

Levels 11 and 14

At level 11, Improved Cunning Strike lets you use two effects on one hit, "paying the die cost for each effect." At level 14, Devious Strikes adds Daze (2d6), Obscure (3d6) and Knock Out (6d6):

The target must succeed on a Constitution saving throw, or it has the Unconscious condition for 1 minute or until it takes any damage.

A level 14 Rogue has 7d6, so Knock Out leaves 1d6. The effect happens after the damage, so your own hit doesn't wake the target. With Dexterity 20 and Proficiency +5, the DC is 18: the Ogre fails 70% of the time, the Bandit Captain 75%. Then the Unconscious condition takes over:

Attack rolls against you have Advantage.

Any attack roll that hits you is a Critical Hit if the attacker is within 5 feet of you.

The first hit wakes it, but that hit is a Critical Hit if it comes from within 5 feet. Knock it out on the turn before your hardest-hitting ally acts.

Quick answers

• Once per turn, on a hit with a Finesse or Ranged weapon.
• Advantage, or an ally within 5 feet of the target and no Disadvantage.
• 1d6 at level 1, +1d6 every odd Rogue level, 10d6 at 20.
• A Critical Hit doubles the Sneak Attack dice.
• An Opportunity Attack on an enemy's turn can Sneak Attack again.
• From level 5, spend dice on Trip, Poison or Withdraw; you choose before rolling.

Every Sneak Attack starts with one d20 against AC. The Book of Dice covers the d20 in Part I, The Object.

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License.