This game was a breeze using FrozenStalker's Builder deck, with a couple minor adjustments (I removed a couple of wains and added some magic walls, and then also added golden bricks once they were available.) This game drags on far too long for how little variety there is between different levels, and even different campaigns.
The "Bunny Rush" method works for much for every level, including the bosses. Just rapid spawn as many bunnies as you can, and an occasional turtle or dragon to take the damage. Food staff and food ring help.
The spiked walls in the Kraken's Cave are incredibly annoying, I can't use the Ram for fear of going into the wall, and if you enter the portal at the wrong angle you're dead at the start.
Easiest way to do this game is give up. Once you've tried and failed, you're going to keep seeing it as the failed way. If you give up and come back, you'll see it in a new light and eventually solve it.