I would also post the aura information
For instance
Devotion Aura - Basically makes all friendly units around the caster as well as the castor gain +(1-5) bonus armor points, this keeps them in battle longer.
Brilliance Aura - An aura that enhances mp regeneration , allows all spellcasters to re-gain their mana at a fast rate, thus cast more spells, extremely useful but only for spellcasters
Endurance Aura - An aura that enhances both attack rate and movement speed, is quiet useful when given to the right units. (Allows units to run slightly faster, and attack at a faster rate, this results in more damage done in a faster time, thus makes the unit under the effect of endurance aura better damage dealers then their counterparts not under the effect of the aura)
Command Aura - Increases all friendly units attack by a percentage, really useful as it can make tier 1 units deal damage like they are tier 3 units
Unholy Aura - Increases hp regeneration and movement speed, is really good because it enhances a units hp regeneration thus allows it to battle longer and heal faster outside of battle, can be very useful
Vampiric Aura - Allows the hero and all melee units to regain a percentage of their attack, really useful for melee attackers, useless for ranged units
Trueshot Aura - An aura that enhances the attacks of ranged units by a certain percentage, basically a copy of the command aura but for ranged only, can be useful if you have lots of ranged units
Thorns aura - An aura that returns a percentage of any melee attacker's attack that is done on any unit which is under the effect of this aura, this is extremely useful as it allows the caster as well as a few units a decent defense against melee attackers.
Any good defense unit needs to have a thorns aura imhm as
@pyf would say