This question is somewhat related to Can you get Sneak Attack with any weapon as a Swashbuckler?
One of my players is a Swashbuckler Rogue, and we debated if he could use the Sneak Attack on every attack with the Rakish Audacity ability (from the Sword Coast Adventurer's Guide):
In addition, you don't need advantage on your attack roll to use your Sneak Attack if no creature other than your target is within 5 feet of you. All other rules for the Sneak Attack class feature still apply to you.
Here are the Sneak Attack rules:
Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must
use a finesse or a ranged weapon.
You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll
So, the original ability removes the advantage requirement if an ally is within 5 feet of the target, and the Rakish Audacity removes the advantage requirement if no other creature is within 5 feet of the Swashbuckler.
Does it mean that the Swashbuckler can use Sneak Attack every turn on an isolated target ? (assuming he uses a finesse weapon, of course)
PS: the party is now level 6, and with this ability, the rogue really does a lot of damage compared to his fellows (paladin, cleric, fighter and wizard.. ok, maybe not the wizard, but still)
Best Answer
No, because the two conditions do not encompass every possibility.
If the Swashbuckler (S) has interposed himself between an Ally (A) and an Opponent (O). Each occupies a single five by five square.
In this scenario, an ally is within 5 feet from the swashbuckler, but there isn't an ally within 5 feet of the opponent. Lacking an additional effect that will provide advantage to the Swashbuckler, Sneak Attack won't be available.
Similarly, if the Swashbuckler (S) is facing two Opponents (O and X), there are several configurations in which Sneak Attack isn't available.
To summarize, the following conditions will prohibit you from using Sneak Attack, assuming there isn't an external effect providing Advantage.
Per a twitter post by Jeremy Crawford, Rules as Intended want the Swashbuckler to be within 5 feet of the target. In effect, Rackish Audacity should be written with "except" instead of "other."