The problem lies with the fact that the spell is summoning
"WildingRider_Group"
There exists no such unit, there is however
"WildingRider_Party"
<SpellDef InternalName="SummonWilding_Ability">
<DisplayName>Summon Wilding</DisplayName>
<Description>Summon a level 4 Wilding Rider</Description>
<Image>SandCrawlerRider_Medallion.png</Image>
<IconFG>Ability_Summon_Wilding_Icon.png</IconFG>
<Cooldown>5</Cooldown>
<SpellBookSortCategory>Summon</SpellBookSortCategory>
<SpellBookSortSubCategory>Summon</SpellBookSortSubCategory>
<SpellType>Tactical</SpellType>
<SpellClass>Offensive</SpellClass>
<SpellSubClass>Summon</SpellSubClass>
<SpellTargetType>EmptyTile</SpellTargetType>
<HideInHiergamenon>1</HideInHiergamenon>
<IsSpecialAbility>1</IsSpecialAbility>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>SummonUnit</Attribute>
<UnitClass>WildingRider_Group</UnitClass>
<Duration>-1</Duration>
<Calculate InternalName="Calc" ValueOwner="CastingUnit">
<Expression><![CDATA[[UnitStat_BonusSummonLevel] + 4]]></Expression>
</Calculate>
<Calculate InternalName="Value">
<Expression><![CDATA[[Calc]]]></Expression>
</Calculate>
</GameModifier>
<AIData AIPersonality="AI_General">
<AIPriority>60</AIPriority>
</AIData>
<HitSoundFX>Spell_SummonDeathDemon_01</HitSoundFX>
<SpellDefEffect>
<EffectName>Y_SummonDeathDemon_Particle</EffectName>
<LocalPosition>0,0,0</LocalPosition>
<EffectScale>1</EffectScale>
<EffectDelay>0</EffectDelay>
<SnapToTerrain>1</SnapToTerrain>
</SpellDefEffect>
</SpellDef>
The bolded unit does not exist at present. Hence the reason the summoning is not working. For those that wouldn't mind editing files, a simple fix would be to change the bolded above to WildingRider_Party. If you like I can make a mod for this.
Edit: Of course I could just make the unit WildingRider_Group and that could fix it as well.
