Sorcerer Subsitution Levels

These substitution levels represent an attempt at mimicking a warlock from World of Warcraft.  New "Fel" spells (some with corrupt components) will be featured in following posts to simulate the warlock's abilities. Instead of creating a whole new class, the decision was made to go for something more flexible and portable. Substitutions and invocations for the D&D warlock class may be created soon.

Now, admittedly, the core sorcerer has few class features to give up in exchange for others that substitution levels typically offer.  So I will have to keep working on this to make it a more balanced trade.
Hit Die: d4.

To take a Fel Sorcerer substitution level, a character must be about to take her 2nd, 3rd, or 4th level of sorcerer.

Fel sorcerer substitution levels have the class skills of the standard sorcerer, plus Diplomacy, Intimidate, Knowledge (planes), Ride, Sense Motive and Use Magic Device.
Skill Points at Each Level: 6 + Int modifier.

Level Base
2nd +1 +0 +0 +3  Forlorn, Fel Spells      
3rd +1 +1 +1 +3  Fel Vitality
4th +2 +1 +1 +4  Fel Affinity

All of the following are features of the fel sorcerer substitution levels.
Forlorn: In exchange for becoming a 2nd-level fel sorcerer, you must forfeit your familiar class feature, and may not gain it later by any means. Any familiar you do have, immediately abandons you without any loss of XP.
Fel Spells (Ex): Starting when you become a 2nd-level fel sorcerer, you may add Corrupt spells as well as spells from the following domains and planar domains to your sorcerer class spell list: Abyss, Baator, Corruption, Darkness, Demonic, Destruction, Diabolic, Evil, Fire, Hades, Pain, Suffering and Summoner.
    Spells that appear on both the cleric class list and sorcerer class list, may also be added to your sorcerer class spell list at the earliest level they become available.
     In addition, you may also add Fel spells to your sorcerer class spell list.
Fel Vitality (Ex): Starting when you become a 3rd-level fel sorcerer, whenever you cast a spell with a Corrupt component, you may minimize any ability damage or ability drain you must suffer as a result, by expending an additional unused sorcerer spell slot of a level equal to or greater than the equivalent level of the spell you are casting.
Fel Affinity (Ex): Starting when you become a 4th-level fel sorcerer, you may cast spells with the Demon, Devil or Fiend component, by replacing it with a Corrupt component that inflicts 1d12 Wisdom damage.
    In addition, you may also add your Charisma modifier to your Will saves instead of your Wisdom modifier.