diff --git a/src/factions/factionClass.ts b/src/factions/factionClass.ts
index f66f67c13..5b1e44d41 100644
--- a/src/factions/factionClass.ts
+++ b/src/factions/factionClass.ts
@@ -1,9 +1,11 @@
+import { uniq } from 'lodash'
 import { TGrandAlliances } from 'meta/alliances'
 import { TSupportedFaction } from 'meta/factions'
 import { TRuleSource } from 'meta/rule_sources'
 import { TSubfactionArmy } from 'types/army'
-import { TEffects } from 'types/data'
-import { TItemDescriptions } from './factionTypes'
+import { SELECTION_TYPES, TEffects } from 'types/data'
+import { TSelectionTypes } from 'types/selections'
+import { TItemDescriptions, TItemKey } from './factionTypes'
 import { getAggregateArmy, temporaryAdapter } from './temporaryAdapter'
 
 /**
@@ -54,6 +56,28 @@ export class Faction<
       a[subFactionName] = temporaryAdapter(this.SubFactions[subFactionName], subFactionName, this.flavorLabel)
       return a
     }, {} as Record<K, TSubfactionArmy>)
+
+    this.checkForDataEntryErrors()
+  }
+
+  /** Throw an error if we've got bad data (this will discover bad data entry) */
+  private checkForDataEntryErrors = () => {
+    const validSelectionKeys: TItemKey[] = [...SELECTION_TYPES, 'allied_units']
+
+    this.subFactionKeys.forEach(k => {
+      const allKeys = uniq([
+        ...Object.keys(this.SubFactions[k]?.available ?? {}),
+        ...Object.keys(this.SubFactions[k]?.mandatory ?? {}),
+      ]) as TSelectionTypes[]
+
+      allKeys.forEach(selection => {
+        if (!validSelectionKeys.includes(selection)) {
+          throw new Error(
+            `${this.factionName} subfaction ${k} has an invalid/unknown key: ${selection}. Please check your data in this faction's subfactions.ts file`
+          )
+        }
+      })
+    })
   }
 }
 
diff --git a/src/factions/skaven/subfactions.ts b/src/factions/skaven/subfactions.ts
index 0936b2e1f..18fbb9784 100644
--- a/src/factions/skaven/subfactions.ts
+++ b/src/factions/skaven/subfactions.ts
@@ -23,7 +23,7 @@ const subFactions = {
       endless_spells: [EndlessSpells],
       flavors: [Flavors],
       grand_strategies: [GrandStrategies],
-      Prayers: [Prayers],
+      prayers: [Prayers],
       scenery: [Scenery],
       spells: [Spells],
       units: [Units],
diff --git a/src/tests/getArmy.test.ts b/src/tests/getArmy.test.ts
index 9a6ee4b5e..cfc34847b 100644
--- a/src/tests/getArmy.test.ts
+++ b/src/tests/getArmy.test.ts
@@ -2,6 +2,7 @@ import { GenericEndlessSpells, GenericTriumphs } from 'generic_rules'
 import { sortBy } from 'lodash'
 import { ORDER } from 'meta/alliances'
 import { BEASTS_OF_CHAOS, SERAPHON, SYLVANETH } from 'meta/factions'
+import { getFactionList } from 'meta/faction_list'
 import { IArmy } from 'types/army'
 import { getAllianceItems } from 'utils/getArmy/getAllianceItems'
 import { getArmy } from 'utils/getArmy/getArmy'
@@ -49,3 +50,9 @@ describe('getArmy', () => {
     expect(shouldNotHaveThisUnit).toBeUndefined()
   })
 })
+
+describe('getFactionList', () => {
+  it('should not throw errors when using getFactionList', () => {
+    expect(getFactionList).not.toThrow()
+  })
+})
diff --git a/src/types/data.ts b/src/types/data.ts
index 28763577c..faf453779 100644
--- a/src/types/data.ts
+++ b/src/types/data.ts
@@ -41,6 +41,25 @@ export const ENTRY_PROPERTIES: TEntryProperties[] = [
   'unit',
 ]
 
+export const SELECTION_TYPES: TSelectionTypes[] = [
+  'artifacts',
+  'battalions',
+  'command_abilities',
+  'command_traits',
+  'core_rules',
+  'endless_spells',
+  'flavors',
+  'grand_strategies',
+  'incarnates',
+  'monstrous_rampages',
+  'mount_traits',
+  'prayers',
+  'scenery',
+  'spells',
+  'triumphs',
+  'units',
+]
+
 export const lowerToUpperLookup: Record<TSelectionTypes, keyof TCollection> = {
   artifacts: 'Artifacts',
   battalions: 'Battalions',