I'd be happy dropping the skill check to neutralize it. To be honest, I'd allow something more broad than magic that removes stun. What about anything that eliminates exhaustion? That gets restoration, greater restoration, and heal (etc).
OK, a few notes from the original text:
1) Usually created and under command of creator.
2) Sometimes formed spontaneously. Hmmm, sounds like any undead. Maybe we need to pick something more interesting. I do like the "will themselves back" angle.
3) Completely focused on killing dragons, but sometimes keeps company of undead dragons.
Hmmm. Seems like we might need an SQ to explain it losing power if it doesn't kill a dragon often enough. What do you think?
Necessary Slaughter (Su): Blood warriors must kill to maintain their strength. If a troop of blood warriors fails to kill sentient creatures with Hit Dice totaling at least that of the troop\'s Hit Dice each week, each member of the troop gains one positive level.
Additionally, should a blood warrior be destroyed, each remaining member of the troop gains one positive level.
When the troop slays a number of Hit Dice of sentient creatures equal to its own total Hit Dice, each member of the troop removes one positive level. If a blood warrior currently has no positive levels, it gains one negative level.
Undead react to positive levels the way nonundead react to negative levels. An undead character with positive levels at least equal to its current level is instantly destroyed. After 24 hours, an undead must make a DC 18 Will save. If the saving throw succeeds, the positive level goes away with no harm to the creature. The afflicted creature makes a separate saving throw for each positive level it has gained. If the save fails, the positive level goes away, but the creature\'s level (or HD) is also reduced by one.
A blood warrior with a negative level gains a +1 competence bonus on all skill checks and ability checks, attack rolls, and saving throws, and gains one effective level or Hit Die (whenever level is used in a die roll or calculation) for each negative level. A spellcaster gains one spell slot of the highest level of spells she can cast and (if applicable) one prepared spell of that level. These gains persist until the negative level goes away (is removed by the gain of a positive level). A negative level that is not removed by a positive level for 3 weeks becomes permanent, resulting in advancement by 1 HD.
We have something similar for blood warriors in the CC:
Want to shorten this?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.