I always need to play a couple of times to fully 'min' 'max' the game the way I'd like to!
I am learning new things even now! That is what I love about the game. Tons of flexibility and different options. Are there overpowered strats? Sure, but you can make do without using them. I suppose the overall main strat is the same, but that's really the same for every video game.
I JUST finished the "50 battles without spellbook" achievement as a mage. I didn't think I could do it with the same army. Good thing I kept a LOT of weaker stacks around.
I hope I can still get the 10M gold achievement. I only have 3M gold right now and there are only like 2 more islands.

I wonder if I should start wearing those +% gold items or not.
I am also mildly worried I won't be able to hit level 70. Maybe I should start making some Ancient Knowledge Scrolls. Plus the final achievement of NOT using a spellbook to defeat the last boss makes me think I have to use a "cheap" rune mage build with paladins to win.
That said, supposedly in Loki's description he is "immune to fire". Well, thank goodness he wasn't since I was dropping flame arrows and fire rain all day on him. He IS resistant though (maybe 20-30% resistant). Not sure if he had physical resistance though. No matter. His defense was no match for my 350 attack Ancient Phoenix.
Yah, Polar Bears is what I used to take out the Giant Spider too. The game really allowed a lot of different items.