Kraxis can be kinda strong ... I mean I don't know exactly when the +10 defense activates on trained units (I think its half of total unit HP as intended, but not sure/not confirmed) ... but its certainly helped them out in the early game battles (like before the better warfare techs, like, say Blacksmithing or Weaponsmithing), or before metal is plentiful enough to build those things ...
in any case, during the days of leather, and the early days of metal, that Kraxis trait can come in hand. Also, the Fortress that gives units impulsive trait for free? epic .... massive armies of slaves destroyed by enemy Kraxis Archers with Impulsive ><
Was fun to build counters ... like leather armor "Slave Soldiers" armed with a +4 intiative dagger (and charge, and +15 strength, and +2 initiative).
and hot damn, at only 1 metal apiece, I was crakin those Slave soldiers like no tomorrow.
For whatever reason I had a huge surplus of gold, so usually I'd just pay the rush costs (at least on the front lines). And boy were they worth it
pretty awesome war.
I think I lost like 3, 4, or even 5 cities before my army reached their capital and conquered it. Part of the problem was that I wasted a lot of time fighting them up north (where they had many outposts and only 1 city) .... and being pretty late in attacking their south (where they had at least 2 size 5 cities ... and even more cities post peace that I haven't even found yet).
By the time I took out their capital ... they had recaptured all the cities I had taken from them in the early stages of the war. My spear slaves simply weren't enough. I needed more power (aside from my Sovereign army of course).
Therefore I designed and trained a few frost mages, as well as TONS of slave soldiers. I had only 3 cities, but between the new troops and plentiful use of that initial Strategic fire spell (pillar of fire?) I was able to put on the pounding 
I think I started that war with 2000 mana, and by the time it was over (everyone had declared war on me at least once during this) ... I had maybe 300 mana.
During my war of vengeance I went down to 20 mana ... and yea. I'm making tons of mana, but using it even faster. Its really hard to save mana 
at least I'm making around 200 gold on low taxes due to my free slaves 