The blood ability is defined in each UnitType.

    <UnitType InternalName="Generic_Sovereign_Altarian_Female">
        <DisplayName>Altarian Sovereign</DisplayName>
        <Class>Sovereign</Class>
        <CreatureType>Champion</CreatureType>
        <RaceType>Race_Type_Altarians</RaceType>
        <CanBeDesigned>0</CanBeDesigned>
        <Gender>Female</Gender>
        <HasWages>0</HasWages>
        <IsSovereign>0</IsSovereign>
        <HasEssence>1</HasEssence>
        <GameModifier>
            <ModType>Resource</ModType>
            <Attribute>Unrest</Attribute>
            <Value>-10</Value>
            <Provides>-10% Unrest in the city this unit is in</Provides>
        </GameModifier>
        <GameModifier>
            <ModType>Player</ModType>
            <Attribute>AbilityBonus</Attribute>
            <StrVal>A_FactionPrestige</StrVal>
            <Value>0.5</Value>
            <PerLevel>1</PerLevel>
            <Provides>+0.5 Faction Prestige per Level</Provides>
        </GameModifier>
        <LevelMilestone InternalName="L1">
            <Level>1</Level>
            <UnitStat_Accuracy>75</UnitStat_Accuracy>
            <UnitStat_CombatSpeed>22</UnitStat_CombatSpeed>
            <UnitStat_ChanceToCrit>1</UnitStat_ChanceToCrit>
            <UnitStat_HitPoints>15</UnitStat_HitPoints>
        </LevelMilestone>
        <SelectedAbilityBonusOption>Blood_Altarian</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>TrainHenchmen</SelectedAbilityBonusOption>
        <Equipment>K_Female_Head_01</Equipment>
        <Equipment>Sovereign_Shoulder_Length_Hair</Equipment>
        <Equipment>Short_Sleave_Shirt</Equipment>
        <Equipment>Country_Corset_ID2</Equipment>
        <Equipment>Murchant_Skirt_ID1</Equipment>
        <AIMilitaryStrategy>Swordsman</AIMilitaryStrategy>
        <AnimationPack>FemaleSovereignAnimationPack</AnimationPack>
        <AnimationParticleEffect>HeroPoseFront,_Particle_Ceresa_02,0.0,-2.0,0.0,1.0,EffectAttach</AnimationParticleEffect>
        <BattleAnimationBehavior>Melee</BattleAnimationBehavior>
        <ClothMapScale>1.6</ClothMapScale>
        <ClothPoseIndex>0</ClothPoseIndex>
        <CutSceneDataPack>ReliasCutscenePack</CutSceneDataPack>
        <EyeTexture>gfx\eyes\blinks\eyeblink_f1_brwn.png</EyeTexture>
        <InfoCardBackground>BG_KingdomRugged</InfoCardBackground>
        <ModelPath>Gfx\HKB\Units\K_Female_Mesh_01.hkb</ModelPath>
        <ModelScale>1</ModelScale>
        <MovingSFX>TEMP_KnightMarching1</MovingSFX>
        <OnHitParticleName>Bloody_OnHit</OnHitParticleName>
        <SkeletonPath>Gfx\HKB\Units\K_Male_Skeleton_01.hkb</SkeletonPath>
        <SoundPack>SoundPack_Generic_Female</SoundPack>
        <TacticalModelScale>1.5</TacticalModelScale>
        <Texture_Skin>K_Female_Freckles_Texture_01.png</Texture_Skin>
        <UnitModelType>KingdomFemale</UnitModelType>
    </UnitType>