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

[spectacle]

Let's turn the cheese up to 11!

The main limitation on sneak attacking outside of your turn is that pretty much every way of making an attack outside your turn requires that you use your reaction, limiting rogues to sneak attacking twice per round. The only way I know of making off-turn attacks without spending your reaction is the Tunnel Fighter fighting style from Unearthed Arcana, which says:
As bonus action, you can enter a defensive stance that lasts until the start of your next turn. While in your defensive stance, you can make opportunity attacks without using your reaction
With this ability you can potentially sneak attack every turn if an enemy obliges by triggering an opportunity attack. You can't usually expect enemies to be so helpful, but there's a way around it, the Polearm Master feat, which says : While you are wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach.
The feat doesn't actually require you to make the opportunity attack with the polearm you are wielding, so if you wield a quarterstaff in one hand and a rapier in the other, you can make an opportunity attack with the rapier against any enemy that enters your reach, triggering Sneak Attack if you hit. If you have the tunnel fighter stance active your can do this to every enemy that enters your reach, potentially sneak attacking many times per round!

I would never allow this at my table since it relies both on an optional rule from UA and a highly questionable reading of the PM feat, but it is fun to speculate

 

[jaelis]

The feat doesn't actually require you to make the opportunity attack with the polearm you are wielding, so if you wield a quarterstaff in one hand and a rapier in the other, you can make an opportunity attack with the rapier against any enemy that enters your reach, triggering Sneak Attack if you hit.

Better with quarterstaff and whip, no? Get the 10 ft reach Plus bonus cheese because you aren't even threatening at 10 ft with the staff.

 

[zaratan]

RAI by Jeremy Crowford won't form, because you need to attack with the polearm. Like war caster + PM.

But RAW...

 

[mellored]

There are a few ways to force an opportunity attack.

Dissonant whispers, command (flee), dominate, fear.... possibly a few more.

And (greater invisibility) + hidden. Which doesn't "force" one, but it's much more likely that a creature will move out of your reach if it doesn't know where your reach is.

 

[Guythegard]

Buy the way, the Cleric Order Domain gives your alias an attack wen you target them with a spell, combine that with silvery barbs which targets an enemy and an ally as a reaction.
you can target your Rogue, give him advantage, and even have him attack thus giving him a sneak attack only with your reaction.
Takes a bit of optimizing tho.

 

[Horwath]

Buy the way, the Cleric Order Domain gives your alias an attack wen you target them with a spell, combine that with silvery barbs which targets an enemy and an ally as a reaction.
you can target your Rogue, give him advantage, and even have him attack thus giving him a sneak attack only with your reaction.
Takes a bit of optimizing tho.

not a lot really.
Variant human or custom lineage, take Fey touched feat, you have that at 1st level.

but, also:

 

[Seramus]

Does this post count as attacking outside of your turn?
It's like a readied action going off 7 years later!

 

[aco175]

Does this post count as attacking outside of your turn?
It's like a readied action going off 7 years later!

But, still do not call it a new edition.