Arrows in Heroes 2.

I'm a bit puzzled by the 25 hit points of the liches. Yes, they have excellent defense – 12, they deal decent damage (8-10), their attack is 7 (which isn't that bad), and their speed is above average (5), but still, 25 hit points combined with a cost of 750 seems a bit…
Just one lightning bolt with a magic power of 6 takes down six liches, which amounts to 4,500 gold!!!
And what do you think about the mages and trolls (just to reiterate, I'm talking about the unupgraded archers of the fifth level)?