The concentration dc is 20+spell level.<br/>The concentration check is 1d20+caster level+ability score tied to your spells.<br/><br/>That would average a 50:50 chance of success without N'Dara's bonded item.<br/><br/>Victoria is fighting guards 10-15 feet from the armory door...more like slaughtering but they weren't meant to be overpowered or even moderate threats.