Flanking

An instance of a hero attacking a monster who has already been attacked from an opposing angle of 90 to 270 degrees. Flanking attacks have 100% hit chance.

Arrow shadows are left drawn on the floor indicating the direction of previous attacks a unit has received this turn.

Interfusion attacks don't get flanking accuracy bonuses. Attacks from interfusions do give flanking bonuses for subsequent attacks, based on where the item interfused with attacked from in most cases (not the caster or center of AOE).

For enemies and objects that are more than 1 tile large, the direction of attack is calculated from the dot in their exact center.