Flanking is a term in Pillars of Eternity 2: Deadfire.
Flanking occurs any time two attackers Engage an opponent in melee from opposite directions. When this situation exists, defenders are Flanked, inflicting various penalties and allowing them to be Sneak Attacked. Any condition on an attacker that would break his or her Engagement will also remove the Flanked condition on the defender if it cannot be sustained without him or her.
Note that there are a small number of Abilities that grant exceptions to the standard flanking rules, such as the barbarian's One Stands Alone, the ranger's Stalker's Link, and the cipher's Phantom Foes.
Flanking Notes & Tips