“Does the spell-casting ability count just for purposes of XP or also for creation cost (and, more importantly, the cap on special abilities)? Put another way, if one turned a non-spellcaster into an intelligent undead (of a type that probably should retain casting like a vampire or lich) and an arcane spellcaster into the same exact type of intelligent undead, would the spellcaster cost more because he keeps his spellcasting, even though the process was, in theory, identical? Does the necromancer need to go through extra steps to ensure that the subject retains his or her casting?”
I fear that the rules are vaguely written here, and thus susceptible to many interpretations. My intended result (which can hardly be deduced from the rules) is that the necromancer must pay the additional cost and time for any special abilities granted due to the ability to cast spells being retained, but that this special ability cost does not count against the maximum number of special abilities that a necromancer may imbue.
EXAMPLE: Sebek would like to transform his minion Thaddeus, a 9th level mage, into an undead creature. Sebek is 14th level and has INT 18 (+3), so he can transform Thaddeus into an undead of up to 14 HD with up to . He opts to transform Thaddeus into a Vampire (9HD).
It will normally cost (2000gp x 9) + (5000gp x 4) 38,000gp and 38 days to transform Thaddeus into a vampire. The target value for Sebek’s magic research throw is increased by 7.
However, Sebek feels that Thaddeus’ spellcasting abilities are too useful to give up, so he takes the extra steps necessary to ensure these will be retained. These count as 2 extras special abilities. Therefore it costs (2000gp x 9) + (5000gp x 6) 48,000gp and 48 days to transform Thaddeus. The target value is increased by 9.
“Furthermore, what would you rate abilities like a phalactery (allowing automatic, if delayed, resurection), undead abilities, etc. (maybe paralysis or fear aura) in terms of “special abilities”? Something like a lich seems to be in danger of hitting ability cap quickly with ** for arcane casting.”
I would assign a lich between *** and **** special abilities, depending on which variant you are adapting (is its paralysis permanent, for instance?) A phylactery is a * special ability.
In general, the more powers a creature has, the less any one power is going to increase it by an *. For example, if a creature can both “control winds” and “telekinesis” this is not twice as helpful as just being able to do one or the other. The ability to both “lightning bolt” and “flame strike” is definitely not twice as good, etc. A Venerable Dragon which can cast arcane spells is a ***** creature.
“Lastly, how do you set the turning roll for a custom undead? Is it HD, special abilities, xp, something else?”
As a rule of thumb, start with its HD. Add 1HD if intelligent. Subtract 1HD if incorporeal. Add 1HD if it’s “hard to turn” or subtract 1HD if it’s “easy to turn”. (Judge’s choice). Compare the result to the following table:
Modified HD - Undead Turned As
1HD - Skeleton
2HD - Zombie
3HD - Ghoul
4HD - Wight
5HD - Wraith
6HD - Mummy
7HD - Spectre
8HD - Vampire
9HD - Infernal
EXAMPLE: A Zombie has 2HD. 2HD monsters are turned as Zombies.
EXAMPLE: A Ghoul has 2HD. It’s intelligent (+1HD). It’s effectively a 3HD monster. 3HD monsters are turned as Ghouls.
EXAMPLE: A Wight has 3HD. It’s intelligent (+1HD) so it’s a 4HD monster. 4HD monsters are turned as Wights.
EXAMPLE: A Mummy has 5HD. It’s intelligent (+1HD) so it’s a 6HD monster. 6HD monsters are turned as Mummies.
EXAMPLE: A Spectre has 7HD. It’s intelligent (+1HD) but it’s incorporeal (-1HD), so it’s at 7HD. 7HD monsters are turned as Spectres.
EXAMPLE: A Wraith has 4HD. It’s intelligent (+1HD), it’s incorporeal (-1HD), but it’s “hard to run” (+1HD) so it’s at 5HD.