Extract Essence is a trait that grants a spell upon the destruction of a defense tower. Each tower gives a different spell, and each can determine the battle outcome. Spells like Chain Lighting grant a random spell within the destroyed towers. Spell Flux won't give a new spell based on the targeted tower. Towers destroyed by Freeze won't grant a new spell. Every time a spell is stolen, half a Rage bar is gained.
Spell stolen[]
Lumber Mill - Cure Poison
Sheep Farm - Rejuvenate
Totems - Rejuvenate
Archer Tower - Southern Cross (Light)
Cannon Tower - Uproot (5 second cooldown after reverting to Extract Essence)
Storm Tower - Northern Lights (Light)
Ballista - Wind Wall
Trebuchet - Earthquake (5 second cooldown before reverting to Extract Essence)
Lightning Tower - Chain Lightning
Red Mage Tower - Reverse Projectiles
Blue Mage Tower - Shield Blast
Ice Turret - Chaos
Fire Turret - Spell Flux
Dragon Perches - Southern Cross (Light)
Dark Flak Tower - Vampiric Touch
Fire Flak Tower - Chaos
Ice Flak Tower - Freeze
Electro-Flak Tower - Chain Lightning
Earth Flak Tower - Northern Lights (Light)