Necromancer/angel and abomination ?
Ok I think I forgot how this works and im to lazy to go check but the demon turns into an angel by doing good deeds the beastmen into an abomination by bad deeds and you actually have to find a way of turning into a necromancer right.( their is more to . this question just gotta wait till i get my answer
As a demon, start going into neutral direction (you need to travel to Syndesia to change yourself into neutral and beyond), then become good from neutral, then do some sort of divine quest for your redemption and embrace your new form - which will lock you from ever doing anything considered evil.
As a beastmen, start going into neutral direction (you need to travel to Syndesia to change yourself into neutral and beyond), then become evil from neutral, then do some sort of offering to Babilis quest to embrace her gift and becoming an abomination - which will lock you from ever doing anything considered good.
As a human, be whatever you want - good, neutral, evil - does not matter at all. Pursue knowledge, find the way to achieve eternity and lichdom - become a lich with no way of turning human back, but you are still free to be good/neutral/evil to your heart's content, although you might no longer have a heart to speak of. #no
The details as to what will be the quests to attain the forms are as of now still unknown and it will probably take some time before they are finalized.