When the RC vampire kills an opponent they rise as 7 HD vampires with half the creatures previous hit points. This can result in 3 hit point 7 HD vampires. Seems kinda silly, so here's an alternate take on vampire spawn.
Vampire Spawn (aka Lesser Vampire)
Hit Dice: 2** (M)
Move: 120' (40')
Flying: 180' (60')
Attacks: 1 touch
Damage: 1d8 + energy drain
No. Appearing: 1d4 (2d4+2)
Save As: F2
XP Value: 45
Monster Type: Undead
Vampire Spawn are the creations of powerful Vampires. They are a vampire liege's trusted lieutenants, sent to scout and hunt, used to defend their lairs, and ruthlessly tossed aside as needed to serve in whatever the lords plans are.
Abilities of Vampires: Vampire Spawn are unaffected by sleep, charm, and hold spells, and can only be damaged by fire, silver & magical weapons, and spells. A vampire spawn may take the form of a human, a wolf, or a giant bat. Each change takes 1 round. Whatever its form, a vampire spawn regenerates 1 hit point per round, starting as soon as it is damaged. If a vampire spawn is reduced to 0 hit points it will fall unconscious and continue to regenerate until the conditions below are met.
In wolf or giant bat form, the vampire spawn's move, attacks, and damage are those of the animal. The vampire's AC, Hit Dice, morale, and saving throws remain unchanged.
Any character slain by a vampire spawn will return from death in three days, as a vampire spawn under the control of the Vampire Liege.
Weaknesses of Vampire Spawn: A vampire Spawn cannot come within 10 feet of a strongly presented holy symbol, although it can move to attack from another direction. The odor of garlic repels a vampire spawn; the creature must make a successful saving throw vs. poison or stay at least 10 feet away from the garlic during that round.
Vampire Spawn cannot cross running water, either on foot or flying, except at bridges or while in their coffins. During the day, a vampire spawn usually rests in its coffin; failure to do so results in the loss of 2d6 hit points per day. These hit points are not regenerated until the vampire spawn has rested in its coffin for a full day. A vampire spawn casts no reflection and avoids mirrors.
A vampire spawn may be destroyed by driving a wooden stake through its heart, decapitation, or by immersion in running water for 1 turn. If a vampire spawn is exposed to direct sunlight, the creature must make a saving throw vs. death ray each round or disintegrate. A continual light spell will not disintegrate a vampire. If all of the vampire's coffins are blessed or destroyed, the vampire spawn will weaken, taking 2d6 hit points of damage per day. It dies when its hit points are reduced to 0.
If a vampire spawn's creator is destroyed, the spawns all become free willed undead. There is a 10% chance that a free spawn will become a full vampire after it has rested in it's coffin for one full day after being freed.
Well that turned out to be longer than I thought it would. Seems like a lot of text for a 2HD monster. Any suggestions on cutting that down?