I did this exact thing but how I did it was make a new faction, and then I edited the tech trees and made 2 new study items called Clarity 1 and Clarity 2 that they studied to increase the mana regen 1 point for each level you invested in it.
I edited 3 files to get this to work for my new race.
1. First I edited the faction xml file for me it was Faction_DragonBorn.xml for you it will be whatever you name the factions.
I added this to the race file. <TechTree>TechTree_DragonBorn</TechTree>
2. I edited the TechTree_Ammarion file and changed the name to TechTree_DragonBorn.
Also you have to edit the INTERNAL NAME in the file to TechTree_DragonBorn.
Next you add the tech's that you would like to add in the file. Here I put
<Tech>Refined_ManaRegen_DragonBorn</Tech> in the file.
<Tech>Refined_ManaRegen_DragonBorn2</Tech>
3. Next step you have to edit the Techs_Ammarion file and define what these 2 new techs do. I did this by adding this to the file.
<TechDef InternalName="Refined_ManaRegen_DragonBorn">
<DisplayName>Clarity</DisplayName>
<Description>This breakthrough gives our sovereign the ability to regenerate 1 extra mana per turn.</Description>
<Image>FireCrystal_Medallion.png</Image>
<Rarity>100</Rarity>
<Category>Magic</Category>
<Infinite>0</Infinite>
<AppearanceChance>100</AppearanceChance>
<GameModifier>
<ModType>Player</ModType>
<Attribute>AbilityBonus</Attribute>
<StrVal>A_ManaRegeneration</StrVal>
<Value>1</Value>
<Provides>+1 Mana Regeneration</Provides>
</GameModifier>
<AIData AIPersonality="AI_General">
<AIResearchPriority>50</AIResearchPriority>
<AITradeToGetValue>75</AITradeToGetValue>
<AITradeOutValue>90</AITradeOutValue>
<AIAtWarMultiplier>1.0</AIAtWarMultiplier>
<AIEarlyBuildUpMultiplier>1.0</AIEarlyBuildUpMultiplier>
</AIData>
</TechDef>
And here is what it does:
TechDef InternalName is the real name of the tech and how the computer knows to look for it.
DisplayName is what the game displays as the techs name.
Category Magic says what branch you research in order to learn this tech.
<GameModifier> Means it modifies something in the game.
<ModType>Player</ModType> modifies a players attributes.
<StrVal>A_ManaRegeneration</StrVal> this affects the mana regen outside of combat there is a seperate one for inside combat.
<Value>1</Value> And by how much.
Here are some other commands that effect mana regen specifically creature abilities.
<PlayerAbilityType InternalName="A_CoreManaRegeneration">
<DisplayName>Core Mana Regeneration</DisplayName>
<Description>How quickly this faction rengerates their core mana.</Description>
<Icon>Icon_Level.png</Icon>
</PlayerAbilityType>
<PlayerAbilityType InternalName="A_ManaRegeneration">
<DisplayName>Mana Regeneration</DisplayName>
<Description>Speed at which all mana regenerates for this nation's people.</Description>
<Icon>Icon_Level.png</Icon>
<DefaultValue>1</DefaultValue>
<UsedAsMultiplier>0</UsedAsMultiplier>
</PlayerAbilityType>
<AbilityBonusOption InternalName = "ArchMage">
<DisplayName>Arch Mage</DisplayName>
<Description>Mana regeneration of the Arch Mage is doubled.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AbilityBonus</Attribute>
<StrVal>A_ArchMage</StrVal>
<Multiplier>2.0</Multiplier>
</GameModifier>
</AbilityBonusOption>
<AbilityBonus InternalName="Regeneration">
<AbilityBonusOption InternalName = "Regeneration1">
<DisplayName>Regeneration</DisplayName>
<Description>This unit regenerates 1 health every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalHealthRegen</StrVal>
<Value>1.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Regeneration2">
<DisplayName>Regeneration II</DisplayName>
<Description>This unit regenerates 2 health every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalHealthRegen</StrVal>
<Value>2.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Regeneration3">
<DisplayName>Regeneration III</DisplayName>
<Description>This unit regenerates 3 health every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalHealthRegen</StrVal>
<Value>3.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Regeneration4">
<DisplayName>Regeneration IV</DisplayName>
<Description>This unit regenerates 4 health every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalHealthRegen</StrVal>
<Value>4.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Regeneration5">
<DisplayName>Regeneration V</DisplayName>
<Description>This unit regenerates 5 health every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalHealthRegen</StrVal>
<Value>5.0</Value>
</GameModifier>
</AbilityBonusOption>
</AbilityBonus>
<AbilityBonus InternalName="Clarity">
<AbilityBonusOption InternalName = "Clarity1">
<DisplayName>Clarity</DisplayName>
<Description>This unit regenerates 1 mana every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalManaRegen</StrVal>
<Value>1.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Clarity2">
<DisplayName>Clarity II</DisplayName>
<Description>This unit regenerates 2 mana every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalManaRegen</StrVal>
<Value>2.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Clarity3">
<DisplayName>Clarity III</DisplayName>
<Description>This unit regenerates 3 mana every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalManaRegen</StrVal>
<Value>3.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Clarity4">
<DisplayName>Clarity IV</DisplayName>
<Description>This unit regenerates 4 mana every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalManaRegen</StrVal>
<Value>4.0</Value>
</GameModifier>
</AbilityBonusOption>
<AbilityBonusOption InternalName = "Clarity5">
<DisplayName>Clarity V</DisplayName>
<Description>This unit regenerates 5 mana every turn during combat.</Description>
<GameModifier>
<ModType>Unit</ModType>
<Attribute>AdjustUnitStat</Attribute>
<StrVal>UnitStat_TacticalManaRegen</StrVal>
<Value>5.0</Value>
</GameModifier>
</AbilityBonusOption>
</AbilityBonus>