Make the tarthans unique by giving them access to an Expert Spell Book: Nature at game start. Other races can access this book but they need to research it: Expert Spell Books > Nature. Program the AI to use this spell book in battle.

Nature refers to magic that allows you to call upon the creatures of the forest.

Level 1

1. Barkskin (tactical) - +5 AC Bonus
2. Summon Wolf

Level 2

1. High Grass (tactical) - Grass 8 fee high grows in one title, attack range of units in this tile is reduced to zero
2. Thorn Grass (tactical) - 6x6 tile that reduces movement rate of units by 1.
3. Summon Bear

Level 3

1. Summon Wolf Pack

Level 4

1. Summon Bear Clan

Level 5

1. Summon Wolf Horde