Wow, reading some of those older threads, it is really fun to see how the old "pros" of King's Bounty Armored Princess clamored to find the best strategies and such.
I remember as a mage I could never beat Ktahu easily in Impossible mode, even with the Black Knights because I was missing Frenzy and the Splinter. Not too many people were able to tell me clearly what was the problem. I wasn't experienced enough to get the answer myself either. They were telling me splinter was the key. It helps a lot, but gosh, who wants to restart their game?
Thankfully, since I've learned the evil game mechanics, I was able to realize my biggest flaw back then was probably totally underestimating the power of -X% in leadership and Frenzy.
One point in Frenzy (to converge to 3X damage), Flaming Eyes, Black Helmet, and EvilN was all I really needed.
-20% in leadership (for units that have > 100ish leadership) is worth FAR more than +damage items.
In fact, leadership is worth far more against the high end bosses than anything else, since the faster you kill them, the better off you are.
You only need one point in frenzy, but if you can slap on more, go for it.
Just saved myself a lot of time. I would have had to drop Agvares and go back for Splinter of Darkness. Whew.
Of course, Splinter would have made the battle much much faster.