It's a very cool idea that desperately needs some balance. (And testing; among other things, I had the Death card, I took a fatal blow, and it reset my health to full and still killed me.)
By taking the Tower card and making five-letter initial plays, it was easy to make four or five letter words along the edge, using the letter I'd put there the previous turn, and score 81x or 243x points. (I think I did over 3300 to some poor goblin.) On the other hand, in the battle against the Sun, I couldn't get a vowel to save my life (literally, since it would have saved my life to get one). I realize that's the luck of the draw,, but that's some pretty severe bad luck there.