This spell causes the dead target (Has to be something with a soul) to resurrect. But instead of normal resurrection this target after touched becomes part of the undead, targeting anyone near it. If a target gets bitten by said resurrected creature after 5 turns of that bitten target (npc or not) it develops the same traits as the original target (Patient 0.)

At latter levels (Level 5+) the infected host ignores the infector  

At 10 the infected ignores both the infector and his/her party

at 20 the infected ignores both the infector and his/her party and the infector gets full control of the infected and its deeds.