From their announcement:
Another tactica is now available: the Decurion (PDF link).
On top of the regular story/stats/skills you find in all tacticas, this first hero overview also details the factions that the Decurion can represent on the battlefield.
Capable of both combat and magic, the Decurion is a well-rounded Hero who should be a no-brainer for most armies.
He can be seen as a duellist capable of going into the thickest melee and easily deal with the enemy’s strongest warriors. Able to boost his Retinue’s capabilities as well as his own, the Decurion should be left as a second wave hitter, sent in only to reinforce the most intense melees, where his presence might mark the difference between victory and defeat. With a high damage output, his deflection and retaliation skills to counter enemy hits and a heavy armour to protect him, he is a Hero who truly shines when facing elite foes.
His Achilles’ heel, however, lies in the fact that he tires quite quickly and should not be sent into a melee with many defensive units where he would lose all efficiency. Moreover sending him to deal with cheap or easy enemy troops is a waste of his potential, especially when another unit could have achieved the same result at a cheaper price.