Escapist Talent. Or Tactical retreat (grants haste for the current turn, so use it first before moving)+The Pawn or other jumps should be enough to escape in one turn.
[Spoilers]
If you answered and talked to the Statue's in the room before the fight, it will tell you that Trompboy is guarding the cave because he is under a curse.
Now, even if you didn't keep that in mind -- if you are observant you'll notice something that should hint a way to solve that seemingly unfair fight.
