Hey! Yes, the final map is a bit hard, I tuned it such that I could finish it (still with some difficulty) after getting all the special items in the game. Here are some hopefully useful hints:
1. Do you have the Amulet of Steadiness? You can buy it from the Amulet shop in the Frostlands.
2. Did you visit the Lost Library (you need the Spectacles to find it). In it you will get some useful bonuses.
3. You can buy a bunch of scrolls. Even non-spellcasters can use scrolls, and they can do so even while stunned, so you can keep a few attack scrolls in the inventory so your front row can use them while they are stunned.
Thanks for playing the game! I hope you make it to the end -- and I hope you make the right decisions in the end sequence in order to save the world hehe :-)