Ive onnly just started and am trying to figure out how to start the main questline, but all i have found on that so far is having a grimoire that you buy from the lich in the tower between the vampire queen and the bear sounding clan, then go to camp, take action, examine spellbook,then you can summon some

Go to the necromancer tower in the North East (Skulzow I think) or the necromancer pyramid on the far south-west (the location with the name in black text) and buy a grimoire (I think it's 2,500 gold or 5,000 or something about that much). Then go to the camp menu, take an action, open your spellbook, and if you have points in necromancy you can summon undead. With higher skill levels giving you more things you can summon and in larger amounts.