These are the counterpoint tospells, weakening the enemy and making them easier to slay. The following applies to hexes:
The target must be an enemy unit.
The target does not have to be within the Wizard's forward arc.
The Wizard does not need line of sight to their target.
The target must be within the spell's range.
Wizards can target spells at units engaged in close combat.
Note that bonuses and penalties from Hex, Augment and other spells are cumulative, but normally cannot take any characteristics above 10 or below 1 unless specified.