Really? Your going to give us an "end fight" that relies on us either solving a puzzle, or beating down a very tough enemy? Sounds very cool.
But then you make the puzzle completely unsolvable more then 50% of the time. Which leaves us only the option of beating down the boss. OHH, but lets give the boss in excess of 50,000 HP, immunity to fire, the ability to bypass AC and displacement, a normal hit of over 100 damage, make him move like a hasted barbarian, and make it so he heals to full power any time he kills a party member.
Turbine, why make an end fight where the puzzle is the focus, and then make most of the puzzles completly unsolvable without attacking the boss. And it seems rather obvious that the goal was to make us work on the puzzle, so that we could get the extra end chest. Seems like an ass backwards plan when you add in a no solution puzzle. Maybe you could just put an intern on the job of removing the 4+ different puzzles with no solution.