The opposite of Enchantment spells, weakening the enemy in some way. Hex spells that require a target can only target enemy units. Most often they affect enemy units, but may occasionally have an effect on friendly units. Casting the same Hex spell more than once on the same unit during the same turn has no further effect.
Note that bonuses and penalties from different Hex and Enchantment spells are cumulative, but cannot take any characteristic above 10 or below 1.