I've now tried and failed at all 12 challenges
That was my first impression as well. So, it isn't too easy, which is good. When I made them and started testing I felt like it was impossible.
I suspect they're all do-able, but they'll all take a lot of runs/practice to complete I think
Now that I played a lot more (approx. 40 runs so far I think), I feel like they are beatable, just require much more tactics and thinking than the regular game (because you have less options than before, and a single missed item/scroll could make a difference between win and loss). Also, choosing a right hero could make a huge difference. And I find that I have to pick different weapons/items to bring to the next level compared to the regular game.
Stomp attacks seem to be super important in IatK and the Bomb-throwing one, but unless you're carrying a voodoo doll everywhere (and you rarely have the inv space) then the boss battles are horrible to deal with unless they're human-size bosses.
I discovered today that it's much easier if you play as a Druid. Just poison the bomb stick/imperial scepter, hit the boss once and watch his HP drain. Now your goal is to maximize the Magic skill to have as strongest poison effect as possible (and maybe Duplicate some Cheese Wedges if possible).
As for the inventory space problem, you can carry a voodoo doll for the Hornet Queen and leave it afterwards, or just repeat the run if you're unlucky to meet her without the doll. You could play as an archer (ditch the bow and arrows for extra inventory space), but I feel like poison is too important and the Snake Staff is the only poison weapon whose poison effect scales with hero skill.
I managed to beat the "Master Blaster" one by getting a bunch of "Money is Power" potions and deliberately allowing a Skeleton Mage to give me Avarice x10 so I can stack up a lot of coins and make the poison super powerful. No need for mana canteen. The only real problem was the Dragon Master because of poison immunity, but by the time I got to him I had enough upgrades to survive. One of the important things was "Drop bombs when hit". I had a lot of HP (around 230) so I just stood in front of his dragon and let him spit fire at me while the dragon master cast his "spear" spell. But even without that, I found a lot of runestones to upgrade the stick and my Melee skill was so powerful, I dealt about 100 damage per hit with that stupid bomb stick.
In a couple of other runs I got the "Bomberman" potion, which makes you throw more bombs. With the Ice Bomb (and optionally Icicle) it makes the whole run almost trivial as you can keep dropping bombs and freeze everything to death. The only problem are the ice-resistant enemies. I usually skip the Ice boss fight with Escape scroll or use Gamble. Of course, if you have poison, it becomes much easier.
I need to test IatK more, perhaps it would really be difficult without Mana Canteen. I have only played it once or twice, so I'm still not sure about that one.
BTW, I managed to reach the Desert boss fight with the "Survival" one. Had Gold Diet (so no problem with hunger) and just stacked potions all the time. I did have to play the whole game with Hypochondria though as I got it early and I didn't want to drink the Dragonfire because it would remove Gold Diet. This was my first time actually fighting the War Elephant in the game (beside testing while development), so he managed to surprise me with his wide ranged attack as I forgot about it
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