Zaharan Update

I’m updating the Zaharan “after the flesh” power to work with all class abilities rather than just spells. Note that this can also work for any characters transformed into monsters, if desired, superseding the rules in ACKS Core at the judge’s discretion.
After the Flesh: Through undeath, the black sorcerers of Zahar can grow stronger. If transformed into intelligent undead, they retain their racial powers and any class abilities. Their class abilities must still be paid for as special abilities.
To calculate how many special abilities the class abilities are worth, total up the number of build points spent in class and racial categories excluding the Hit Dice category. If the total is 1-3 build points, the class’s abilities collectively count as one special ability (). If the total is 4-5 build points, the class’s abilities count as two special abilities (). If the total is 6-7 build points, the class’s abilities count as three special abilities (). If the total is 8 build points, the class’s abilities count as four special abilities ().
Build Points
(excluding HD) # of Special Abilities (
1-3 *
4-5 **
6-7 ***
8 ****
Once transformed, a Zaharan may continue to advance in Hit Dice without limit, regardless of his class’s maximum level. At 1 HD, it requires 3,000 XP plus 500 XP per special ability (
) to advance to 2 HD. The amount of XP required doubles with each HD (round values greater than 20,000 XP to the nearest 1,000).
As the undead Zaharan’s Hit Dice increase, any class abilities (such as thief skills, spellcasting, turning undead, etc.) will continue to progress without regard to his class’s maximum level, to a maximum of 14th level.
EXAMPLE: A Zaharan Sorcerer-Priest is designed as a custom class with all the spellcasting abilities of both a cleric and mage (Hit Dice 0, Fighting 0, Thievery 0, Divine 2, Arcane 2, Zaharan 2). This class costs 6 build points, meaning its maximum level is 11. After many sessions of play, a Zaharan Sorcerer-Priest character has advanced to 11th level. The character then transforms into a mummy by necromantic ritual. The class’s build points, excluding hit dice, are (2+2+2) 6, so retaining the class abilities count as three special abilities. The character is therefore an 11
**HD mummy (11HD because he was 11th level; * from mummy; *** from class abilities). The Zaharan Mummy Sorcerer-Priest then begins advancing in HD. His HD may advance without limit. His class abilities will continue to increase as he gains HD, until he achieves the maximum of 14th level of divine and arcane spellcasting ability.

Also, as a point of clarity, the rules assume that the XP cost for monstrous/undead advancement keeps doubling (unlike human and demi-human classes, which flatten out at 9th level).
For example, in the example of the Sorcerer-Priest above, the XP curve would be:
1 0
2 5,000
3 10,000
4 20,000
5 40,000
6 80,000
7 160,000
8 320,000
9 640,000
10 1,280,000
11 2,560,000
12 5,120,000
13 10,240,000
14 20,480,000
Now, that’s obviously a grossly high amount of XP. My in-world assumption is that most undead aren’t reaching 12th, 13th, 14th level on human timescales – it’s mostly helpful because they can live forever. So even if they’re only earning, say, 10,000xp per month, that will yield 120,000 per year; 1,200,000 per decade; and 12,000,000 in a century.
If you want your PCs to become undead and continue to advance on a human scale you’ll need to flatten the curve out.