Runes
From The Utopian Encyclopedia
Runes are the main resource used in Spell Casting.
Obtaining Runes
Towers generates additional runes per Utopian Day.
Runes can also be taken from an enemy province, via:
Decay and Destruction
After each tick, 1.2% of the total runes in storage will decay.
An enemy province's rune supply can be attacked via the Lightning Strike Spell
note: This attack will not return the destroyed runes.