A ghost and a toothpick
So, whatever your build, Magic Spirit is always one of your spells. It falls under I think "arcane" spells which are available to you no matter what kind of spell books you have. The first thing you should do as soon as possible is cast Magic Spirit to start exploring the map because you can't see anything thanks to the fog of war game mechanic until you go look. If you choose all death books, it takes a few rounds to come up with enough resources to get a Shadow Demon. You will want a Magic Spirit to go with it anyway to double its travel speed. So get a Magic Spirit and start looking around. Especially in the early game, some towns and ruins are unprotected and you can take the loot with a pathetic Magic Spirit. Some are lightly protected and I get a kick out of figuring out which battles I have some hope of winning with a ghost and a toothpick as my army. Remember to save scum. So if you can grab up resources with a Magic Spirit, it can fast track your ability to get...