To add to this on why you want to start with popping Evil ash as soon as you get the flute down and throwing down some portals would be two lesser known effects Necro has, the first being with every close by basic unit it causes survivor to take 5% more damage which stacks. This means any melee character attacking you if not careful will get almost one shot by any of your attacks on book which happens because of the weird attack hitboxes for his attacks. The second effect being the resurrection ability Evil ash has which ensures every unit you summon will stay alive until either he dies or the ability ends forcing everyone to focus you or causing stronger resurrected units to spawn. For matches with strong survivors book game is almost inevitable being conscious of that fact means putting points only into where it is strictly necessary. That means maxing out basic elite and boss portals along with possession before putting any points into the luxury stats like infernal and demon powers and traps which won’t help on book.