The thing about sennen war's guide is he relies on true damage from both AW Rika and Metus. I'm gonna ask you one question: Do you have and raised Rosel (event monster hunter), Celina (event bishop), any ranger, and Rika? I'm assuming you are replacing a magic fencer with Sukuha. If all those girls are battle-ready, then here is a good guide: http://www.nicovideo.jp/watch/sm29475193
Here are other guides that might fit your team. A lot of them rely on slowing him down with necromancer's skeleton tokens or ranger's traps.