You can mod it in yourself (stolen from Gnilbert - should work, I haven't gotten the chance to build them myself):
Put the following XML into your \Mods folder:
Gnilbert_Unit.xml
<UnitType InternalName="RecruitedDeathWarg">
<EyeTexture>gfx/eyes/male_brown_eye.png</EyeTexture>
<!-- base data-->
<DisplayName>Death Warg</DisplayName>
<Quote>'Nothing can outrun death...'</Quote>
<!-- graphical data-->
<ModelPath>gfx/hkb/Monsters/M_Warg_Mesh_01.hkb</ModelPath>
<SkeletonPath>Gfx\HKB\Monsters\M_Warg_Skeleton_01.hkb</SkeletonPath>
<Texture_Skin>M_Warg_Texture_01.png</Texture_Skin>
<EyeTexture>gfx/eyes/male_brown_eye.png</EyeTexture>
<ModelScale>3</ModelScale>
<MaxScaleMainMap>0.8</MaxScaleMainMap>
<AnimationPack>WargAnimationPack</AnimationPack>
<CutSceneDataPack>BigWargUnitCutscenePack</CutSceneDataPack>
<Color_Skin>20,20,20</Color_Skin>
<Medallions InternalName="">
<All>Creature_Ebbenwolf1.png</All>
</Medallions>
<!-- particles-->
<OnAttackParticleName>Bite_Attack</OnAttackParticleName>
<!-- soundFX -->
<SoundPack>SoundPack_Warg1</SoundPack>
<!-- levels -->
<LevelMilestone InternalName="L1">
<Level>1</Level>
<UnitStat_HitPoints>0</UnitStat_HitPoints>
<UnitStat_Attack>3</UnitStat_Attack>
<UnitStat_Defense>2</UnitStat_Defense>
<UnitStat_CombatSpeed>2</UnitStat_CombatSpeed>
<UnitStat_Strength>12</UnitStat_Strength>
<UnitStat_Wisdom>1.0</UnitStat_Wisdom>
<UnitStat_Dexterity>10.0000</UnitStat_Dexterity>
<UnitStat_Intelligence>10.0</UnitStat_Intelligence>
<UnitStat_Charisma>10.0</UnitStat_Charisma>
<UnitStat_Constitution>25.0</UnitStat_Constitution>
<UnitStat_Sight>2</UnitStat_Sight>
<UnitStat_Essence>3</UnitStat_Essence>
</LevelMilestone>
<LevelMilestone InternalName="L30">
<Level>30</Level>
<UnitStat_HitPoints>0</UnitStat_HitPoints>
<UnitStat_Attack>6</UnitStat_Attack>
<UnitStat_Defense>4</UnitStat_Defense>
<UnitStat_CombatSpeed>2</UnitStat_CombatSpeed>
<UnitStat_Strength>22</UnitStat_Strength>
<UnitStat_Wisdom>1.0</UnitStat_Wisdom>
<UnitStat_Dexterity>10.0000</UnitStat_Dexterity>
<UnitStat_Intelligence>10.0</UnitStat_Intelligence>
<UnitStat_Charisma>10.0</UnitStat_Charisma>
<UnitStat_Constitution>50.0</UnitStat_Constitution>
<UnitStat_Sight>2</UnitStat_Sight>
<UnitStat_Essence>2</UnitStat_Essence>
</LevelMilestone>
<SpawnLevel>2</SpawnLevel>
<Backstory>
Plains Wargs are fell creatures mutated by dark magic. They are stronger and more cunning than their non-magical counterparts and continue to wreak havok throughout the wastelands. Unlike normal wolves they prefer to hunt alone and are more likely to fight over territory than group up with their brethren.
Warg Pelts are rare indeed and can be sold to merchants for a fair few gildar.
</Backstory>
<RequiresCityUnlock>1</RequiresCityUnlock>
<ProductionRequirement>
<Type>Resource</Type>
<Attribute>Gold</Attribute>
<Value>50.0</Value>
</ProductionRequirement>
<Prereq>
<Type>BuildingRequirement</Type>
<Attribute>NightwargRecruiting</Attribute>
</Prereq>
<CanBeDesigned>1</CanBeDesigned>
<!-- This lets it show up in the train wnd -->
<IsUniqueButBuildable>1</IsUniqueButBuildable>
<!-- This keeps it out of the unit design wnd -->
</UnitType>
---
