Honestly, this is where the series starts to die. Gen ruined it. He mighta turned out to be an ok character, but the others' growth as Kekkaishi stopped right here when they started/had to rely on him. They really showed some promise last time, but fail to further develop their skills.
I really think the show coulda been so much better without him. Nevermind the total douchebaggary.
Sometimes, even though you want to kill everyone, you have to know that killing just isn't the answer.
I've made that mistake too many times.