It was a khorne allegiance army. Archaeon has all the keywords so receives all the benefits. With the skull alter you can reroll failed prayers. If the warshrine which is a khorne priest is within 8 inch. With the banner you give Archaeon extra attacks but most importantly skarbrand which has the carnage ability, if you roll a 6 it does 16 mortal wounds, with 2 attacks very common. So yeah I would call that a broken army haha.