Abridged Guide to Evil Wikia

The Reforms is the term most commonly used for the changes to the Dread Empire and the Legions of Terror after Dread Empress Malicia took the throne of the empire. 

It, amoung other things, changed the way greenskins were used in the Legions, using their strengths much better, and the general command structure of the Legions. This means that unlike the former Legions, the modern Legions would now be able to lose a general and very quickly replace them, making the structure much more stable.

It is generally thought that the Reforms are the reason for the successful conquest of Callow.

the success of the military reforms caused similar advancement in militaries across Calernia, while many considered the calamites the main instigators of renewed praes military might, some nations like procer had sought to emulate the success of the legions with newly adapted military stratagem.

the reforms also contained a significant civil aspect, with Malicia using her influence to clear lingering corruption in praes civil government and reduce the influence of the Highborn in the running of the empire.

further reforms sought to reduce the predominance of humans and Soninke in particular in the empire and push for equal status for the greenskin members of the empire, with possible ennoblement of clan chieftain being one amongst the possibilities, such further reforms were contested most fiercely by the Highborn, and were one of the friction point between the empress and the nobles of the empire.

during the course of the civil wars, decimation in the Highborn ranks allowed Malicia to push further civil reforms with the ennoblement of certain greenskin loyalist to the throne, through the circumstances surrounding such further reforms were not optimal for the unity and equality of the greenskin populace at large.