Just got rolled by AI Neifel. What did I do wrong?

[Quietly]

I'd also like to suggest you are missing out bigtime in your strategy, in treating your bless troops...

you should have been regularly buying helharkl and vanherses... with w9f9, you can make a perfectly acceptable army of a herse or harkl per 5-7 helhirdlings... you just set them all at the back of battlefield, set the commander to bless 3x, and have the hirdlings hold and attack... 3 blesses is adequate coverage for a small force, and the small force is adequate for taking neutral provinces or normal amounts of pd... you should have many many of these tiny armies roaming everywhere...

you should also have their territories covered in little neutral scouts, so that there is no more suprise armies of giants, and you can take appropriate actions.

the above poster already covered the magical aspect, so thats my 2 cents