Battlecry Ballad

You fill your allies with a thirst for glory and battle using your triumphant rallying cry. Expend and roll a Bardic Inspiration die to determine the number of rounds you can maintain concentration on this spell (minimum 1 round). Each target gains a bonus to attack and damage rolls equal to the number of rounds you have maintained concentration on this spell (maximum +4). 

You cannot cast another spell through your spellcasting focus while concentrating on this spell.