Alright, I've been trying to create a spell that summons a champion using the tag:
<SpellDef InternalName="SummonCelestial">
<DisplayName>Celestial Contract</DisplayName>
<Description>Summons a celestial champion to aid in your cause</Description>
<Image>Escape_Painting.png</Image>
<IconFG>SpellBlast_Icon.png</IconFG>
<IconBG>SpellBlast_Icon_BG.png</IconBG>
<IconColor>64,59,255</IconColor>
<SoundFX>DarklingIdleGiggle3</SoundFX>
<Range>1</Range>
<SpellLevel>1</SpellLevel>
<RequiredStat>UnitStat_Charisma, 14</RequiredStat>
<SpellType>Strategic</SpellType>
<SpellClass>Defensive</SpellClass>
<SpellTargetType>Self</SpellTargetType>
<CastTime>1</CastTime>
<SpellResourceCost>
<Resource>Mana</Resource>
<Amount>48</Amount>
</SpellResourceCost>
<SpellResourceCost>
<Resource>Mana</Resource>
<Amount>1</Amount>
<PerTurn>1</PerTurn>
</SpellResourceCost>
<SpellDefEffect>
<EffectName>SummonLife</EffectName>
<LocalPosition>0,0,0</LocalPosition>
<EffectScale>0.4</EffectScale>
<EffectDelay>0.0</EffectDelay>
<SnapToTerrain>1</SnapToTerrain>
</SpellDefEffect>
<GameModifier InternalName="SummonUnit">
<ModType>Unit</ModType>
<Attribute>UnitJoinArmy</Attribute>
<StrVal>CelestialChampion</StrVal>
<UnitClass>Champion</UnitClass>
<Duration>-1</Duration>
</GameModifier>
</SpellDef>
which references the code (adapted from the EFM generously created and given permission for use by Heavenfall):
<UnitType InternalName="CelestialChampion">
<DisplayName>Celestial</DisplayName>
<UnitDisplayName>Celestial</UnitDisplayName>
<Quote>"Sometimes lost is exactly where you need to be."</Quote>
<ModelPath>Gfx\HKB\Units\K_Male_Mesh_01.hkb</ModelPath>
<SkeletonPath>Gfx\HKB\Units\K_Male_Skeleton_01.hkb</SkeletonPath>
<EyeTexture>gfx\eyes\blinks\eyeblink_m4_grn.png</EyeTexture>
<AnimationPack>SoldierAnimationPack</AnimationPack>
<MountedAnimationPack>MountedSoldierAnimationPack</MountedAnimationPack>
<ModelScale>1.0000</ModelScale>
<EquipmentScale>1.0000</EquipmentScale>
<ClothMapScale>1.2000</ClothMapScale>
<MovementType>Air</MovementType>
<BobbingFrequency>0.0000</BobbingFrequency>
<ClothPoseIndex>1</ClothPoseIndex>
<InfoCardBackground>BG2_Abstract</InfoCardBackground>
<InfoCardBackgroundFlipped>0</InfoCardBackgroundFlipped>
<CanBeDesigned>0</CanBeDesigned>
<UserDesigned>true</UserDesigned>
<MovingSFX>TEMP_KnightMarching1</MovingSFX>
<LevelMilestone InternalName="">
<Level>1</Level>
<UnitStat_Attack>0.0000</UnitStat_Attack>
<UnitStat_Charisma>16.0000</UnitStat_Charisma>
<UnitStat_Constitution>15.0000</UnitStat_Constitution>
<UnitStat_Defense>0.0000</UnitStat_Defense>
<UnitStat_Dexterity>17.0000</UnitStat_Dexterity>
<UnitStat_ExpToNextLevel>20.0000</UnitStat_ExpToNextLevel>
<UnitStat_HitPoints>0.0000</UnitStat_HitPoints>
<UnitStat_Intelligence>13.0000</UnitStat_Intelligence>
<UnitStat_ManaRegen>1.0000</UnitStat_ManaRegen>
<UnitStat_Sight>4.0000</UnitStat_Sight>
<UnitStat_Strength>12.0000</UnitStat_Strength>
<UnitStat_Wisdom>17.0000</UnitStat_Wisdom>
<UnitStat_Essence>1.0000</UnitStat_Wisdom>
<UnitStat_CombatSpeed>2</UnitStat_CombatSpeed>
</LevelMilestone>
<Equipment>expandedfactions_angels_K_Male_Head_01</Equipment>
<Equipment>CPELF_Sovereign_Short_Hair_02</Equipment>
<Equipment>CPELF_Sovereign_Warrior_Shirt_ID1</Equipment>
<Equipment>CPELF_Warrior_Surcoat_ID2</Equipment>
<Equipment>CPELF_Kingdom_Leather_Gloves_Dark</Equipment>
<Equipment>CPELF_Basic_Pants</Equipment>
<Equipment>CPELF_Basic_Boots_Leather</Equipment>
<Equipment>Staff</Equipment>
<!--<Color_Skin>217,153,97,255</Color_Skin>
<Color_Hair>176,122,74,255</Color_Hair>
<Color_Clothing1>0,0,0,255</Color_Clothing1>
<Color_Clothing2>50,50,50,255</Color_Clothing2>-->
<Texture_Skin>K_Male_Default_Texture_01.png</Texture_Skin>
<Texture_Eyes>gfx\eyes\blinks\eyeblink_m4_grn.png</Texture_Eyes>
<Gender>Male</Gender>
<UnitModelType>AngelMale</UnitModelType>
<IsSovereign>0</IsSovereign>
<UnitDisplayName>Celestial</UnitDisplayName>
<NPCTalentValue>2</NPCTalentValue>
<SpawnRating>-1</SpawnRating>
<NPCSpawnLikelihood>-1</NPCSpawnLikelihood>
</UnitType>
</UnitTypes>
And this seems to cause strange things to happen in-game. Such as asking me to update to v1.1 (which I have) and causing Fertile Land tiles to be underwater. I have the Expanded Factions mod in my mods directory.