Glimpses of Hyboria
If multiple opponents attack the same character in the same round, each succeeding attacker (even if the previous attacks in the round do not do damage)receive a +1 to hit. This +1 is cumulative.
Example: if three characters attacked the same target, the first attacker would receive no bonus but the second one would receive a +1, the third would receive a +2 etc.
Note: uncanny dodge and similar feats do NOT negate this +1 circumstance bonus.
Note: this circumstance bonus stacks with flanking bonus.