when we consider that the turtle uses random spells, if you are lucky no damage spells are used
so you can shoot the turle down (also using snake, rogue/bandit attacks over free cell) on the other hand, when you play impossible and will be hit by lighting or fireball, OUCH!
Bur for this there is the secred cheat key : F8
So with good strategy you can defeat the turtle with any level of your hero. (This does not work on Kraken or Big baddy Spidy)