D&D 5E Methods of granting or making attacks outside of your turn

[Illithidbix]

So the Sage Advice, which confirmed something many of us already knew: that you can only Sneak Attack once per turn… but you can get more than one sneak attack out per round if you can get an attack outside of your turn.


The obvious one is of course the Opportunity Attack

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.
You can avoid provoking an opportunity attack by taking the Disengage action. You also don’t provoke an opportunity attack when you teleport or when someone or something moves you without using your movement, action, or reaction. For example, you don’t provoke an opportunity attack if an explosion hurls you out of a foe’s reach or if gravity causes you to fall past an enemy.

The big limiter is in every case I know it requires you to use your Reaction.

Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else’s. The opportunity attack, described later in this chapter, is the most common type of reaction.

When you take a reaction, you can’t take another one until the start of your next turn. If the reaction interrupts another creature’s turn, that creature can continue its turn right after the reaction.

So is inherently limited, and one I believe has been very deeply embedded into 5E.

So… here I have tried to find all the methods of granting yourself or an ally an attack outside of turn order. Triggers in bold.

Commander’s Strike and Inspiring surge are the only methods I can find for granting an ally an attack on your turn.

Barbarian - Level 14 Path of the Berserker

Starting at 14th level, when you take damage from a creature that is within 5 feet of you, you can use your reaction to make a melee weapon attack against that creature.

Fighter

Battlemaster

Commander's Strike

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action to direct one of your companions to strike. When you do so, choose a friendly creature who can see or hear you and expend one superiority dice. That creature can immediately use its reaction to make one weapon attack, adding the superiority dice to the attack's damage roll.

Riposte

When a creature misses you with a melee attack, you can use your reaction and expend one superiority die to make a melee weapon attack against the creature. If you hit, add the superiority dice to the attack's damage roll.

Purple Dragon Knight Level 10 and 17

Starting at level 10, when you use your Action Surge feature, you can choose one creature within 60 feet of you that is allied with you. That creature can make one melee or ranged weapon attack with its reaction, provided that it can see or hear you.
Starting at 17th level you can choose two allies within 60 feet of you, rather than one.

Monk – Level 17 Way of the Shadow

Whenever a creature within 5 feet of you is hit by an attack made by a creature other than you, you can use your reaction to make a melee attack against that creature.

Paladin - Level 15 Oath of Vengeance

When a creature under the effect of your Vow of Enmity makes an attack, you can use your reaction to make a melee attack against that creature if it is within range.

Ranger - Level 3 Hunter

When a Large or larger creature within 5 feet of you hits or misses you with an attack, you can use your reaction to attack that creature immediately after its attack, providing you can see the creature.

Feats

Mage Slayer

When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against the creature

Polearm Master

Whilst you are wielding a glaive, halberd, pike or quarter staff, other creatures provoke an opportunity attack when they enter your reach.

Sentinel

When a creature within 5 feet of you makes an attack against a target other than you (and that target doesn't have this feat), you can use your reaction to make a melee weapon attack against the target.

Martial Adept
See Fighter - Battlemaster above for Commander's Strike and Riposte

Any that I've missed?
And any that don't require you/your ally to use a Reaction to act outside of their turn?

 

[DeathMutant]

How about multi-classing as a Fighter and using Action Surge to Ready an Action to attack again when <an expected event> happens on someone else's turn thus giving you another chance to inflict Sneak Attack damage? The event could be as simple as an ally shouting "Strike!"

 

[Illithidbix]

How about multi-classing as a Fighter and using Action Surge to Ready an Action to attack again when <an expected event> happens on someone else's turn thus giving you another chance to inflict Sneak Attack damage? The event could be as simple as an ally shouting "Strike!"

That's impressively niche but I don't see why it wouldn't work.
And congrats on making the Fighter/Assassin combo even more horrible!

 

[ehenning]

How about multi-classing as a Fighter and using Action Surge to Ready an Action to attack again when <an expected event> happens on someone else's turn thus giving you another chance to inflict Sneak Attack damage? The event could be as simple as an ally shouting "Strike!"

From PHB, pg 72
Action Surge
Starting at 2nd level, you can push yourself beyond your normal limits for a moment. On your turn, you can take one additional action on top of your regular action and a possible bonus action.

So, you can't use this outside of your turn, and you can only have one Sneak Attack per turn.

It's pretty clear that RAW doesn't allow more than two Sneak Attacks (turn and reaction) per round.

 

[spectacle]

From PHB, pg 72
Action Surge
Starting at 2nd level, you can push yourself beyond your normal limits for a moment. On your turn, you can take one additional action on top of your regular action and a possible bonus action.

So, you can't use this outside of your turn, and you can only have one Sneak Attack per turn.

It's pretty clear that RAW doesn't allow more than two Sneak Attacks (turn and reaction) per round.

Ready is an Action you take on your Turn, so the action surge trick works fine by RAW. You're not using Action Surge outside of your turn, you're using your Reaction to make an attack you Readied on your Turn.

Even better than Action Surge is the Haste spell. It gives an extra Action with some heavy limitations on what kind of actions it can be used for, but one of the possibilities is a single weapon attack. A Rogue can use the Action from Haste to make an attack on his turn, and then use his regular Action to Ready an attack to go off on someone else's turn.

Rogues don't get Extra Attack, so the limitation of a single attack from Haste doesn't actually limit them.

 

[ehenning]

Ready is an Action you take on your Turn, so the action surge trick works fine by RAW. You're not using Action Surge outside of your turn, you're using your Reaction to make an attack you Readied on your Turn.

Even better than Action Surge is the Haste spell. It gives an extra Action with some heavy limitations on what kind of actions it can be used for, but one of the possibilities is a single weapon attack. A Rogue can use the Action from Haste to make an attack on his turn, and then use his regular Action to Ready an attack to go off on someone else's turn.

Rogues don't get Extra Attack, so the limitation of a single attack from Haste doesn't actually limit them.

This can apply for standard actions, for sure, but not for Sneak Attack. You are still limited to one on your turn and one on your reaction

 

[UngeheuerLich]

Fighter assasin combo is really not horrible at all. If surprise rules are used correctly. You need to win initiative. After the enemy's first turn it is not surprised anymore.

 

[Horwath]

How about multi-classing as a Fighter and using Action Surge to Ready an Action to attack again when <an expected event> happens on someone else's turn thus giving you another chance to inflict Sneak Attack damage? The event could be as simple as an ally shouting "Strike!"

If a rogue has Action surge, I would just tell him, if he wants to, that on his turn he can just burn action surge and reaction and get sneak attack with second attack.

 

[Cap'n Kobold]

How about multi-classing as a Fighter and using Action Surge to Ready an Action to attack again when <an expected event> happens on someone else's turn thus giving you another chance to inflict Sneak Attack damage? The event could be as simple as an ally shouting "Strike!"

This can apply for standard actions, for sure, but not for Sneak Attack. You are still limited to one on your turn and one on your reaction

It was never claimed otherwise: ready an action always used your reaction. Its a way of getting another sneak attack in a round using your reaction.

Spectacle was just explaining for the benefit of the person who was claiming it wouldn't work because Action Surge only worked on your turn.

 

[zaratan]

Any spell that make the opponent use action/reaction/movement to cause AoO, like dissonant whisppers, command, fear...

If your DM allow unearthed arcana, the most important of all: tunnel fighter.