Once you get to chapter 8 or so, your opponents start having "second winds" where they spit out dozens of paladin-equivalents when their castles get low on health. My suggestion is to advance slowly, using small groups of units, and save up your mana so you can dump out a huge wave of your own guys to counterattack their counterattack.
For those having trouble with Totems (the Orc volcano-making dudes) or the equivalent (elf ice-mages and so on): you need paladins (or the equivalent). Weaker dudes will just be frozen or knocked around by their spells and once your front line breaks your ranged dudes are kind of in trouble. Paladins don't get knocked around as easy so they're kind of needed to keep the front lines stable. No, you can't just target them with your arrows, unless you've got a really high level tower and you're a better aim than me.... which isn't that hard but anyway...
Here's a fun trick that you can try: aim high and fire an arrow, then aim lower and fire at the same target. If you do it right, your arrows will hit the target at the same time! Yes, this can actually happen in real life.
To the guys complaining about the difficulty: it's not really that hard. I didn't even take a hit until Chapter 4 (when I took a grand total of 20 damage. Finishing with 4980 health out of 5000 isn't too bad). If you're having trouble, replay level 1 and practice aiming and upgrading. I really like this game, I haven't had any trouble with auto-fire (clean your keyboards people!) and I'm giving it a solid 5/5 for graphics and gameplay... although I haven't really been paying attention to the storyline all that much. I'm a little too eager to try out the elves, sorry!
Um, correction to my previous review: I meant holding down the "A" button, or whatever the fire button is. My apologies to the three people who read my review.
Good game. Autofire works for me, just by holding down the moouse button. The upgrade is kind of weird, It allows you to upgrade your castle DURING THE LEVELS. You have to get the amount of mana required for the upgrade (100 for the barracks, for example) and then click the icon. I actually like it that way but I wish it mentioned how much the upgrades cost when you mouse over them in game. Overall, I really like it. I don't think it's that challenging, if you're having trouble just replay the first few levels and get some more upgrades.
OK, how is killing 97% of the bad guys not a gold medal? I'm a fan of thoroughness too, but getting 100% bad guys killed on levels this big requires a map. Preferably one with little blinking dots on it so we know who we missed.
The enemies could use an upgrade. They're REALLY easy to kill and it's REALLY easy to dodge their attacks. Overall, 3/5. Add the map and up the baddies and it could be a really fun game.
Purple feels really underpowered. Too many 1 strength creatures with nothing in-color to make them stronger. Needs more multicolor cards, or at least multi-friendly.
I like it but there are two areas I'd improve on. First, the flying guys that can go through the ground. If they come at you from below, it can be a real pain to get rid of them. Second, aiming the necro-hand is for some reason incredibly difficult for me. I've tried to aim it right in front of one of the ground enemies and it always seems to either A) appear much closer to me than I wanted or B) not appear at all, in which case I have to scramble for the lightning spell and usually wind up taking a hit or twelve.
Glitch: I used the Brute +2 power spell and it was permanent for the two ghosts in my back row. Not that I mind having two ranged 4 power creatures, I just thought I should report it.
One thing about the AI: it always goes for the extra turn... which means that the AI likes getting four medusa gems in a row (and thus dealing 8 damage to itself) every chance it gets.
The AI could use a little work. My last game I played the challenge against the white deck. He spent one turn playing medical ward and his next turn destroying it. Two free turns to attack with 4 creatures and nothing to block them? Guess how fast I won.