i just did no. 4
i used
fire demon,dragon rider,frost G., centaur A and bomber
for spells
heal,ice trap,thunder bolt,meteor strike, zues wrath (everything listed max is suggested will only help u more)
when they send the big guys use zues wrath and ice trap,thunder bolt,meteor strike, on them then u get about 30% down then they send out another big guy with wave just keep on the big guy with zues wrath and the other 3 spells and repeat
well this is how i beat it
hope this helps some of you
"There Can Be Only One"
Dude! You just completed the "There Can Be Only One" achievement in Feudalism II and won the "There Can Be Only One" badge and 30 points!
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glich i lost the battle vs the ninja boss and got that badge :D