Flank

From NWNWiki

To flank is to be directly on the other side of a character who is currently attacking another character. A flanking attacker gains a +2 flanking bonus on attack rolls against the defender. A rogue can sneak attack a defender that she is flanking.

For example, suppose characters A and B are attacking one another. Should character C decide to attack either of them, he/she would receive a +2 AB flanking bonus.

[edit] Notes

• The +2 flanking bonus to AB does not count towards the +20 attack bonus cap.
• The Dwarven Defender feat defensive awareness II prevents a character from becoming flanked.