A 506
Oooo I know something Silvanos forgot
Feat - Vexing Flanker is in the PHB II if you're looking for a +4 flanking bonus
I cannot tell you about its prerequisite as it is not in the SRD
another feat I would recomend for you though would be this one which fortunately is.
and there was much celibration and rejoicing... quite disproportionate to the actual achievement
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