Because I'm a masochist, I've been playing around with speed killing the final boss. Nothing particularly interesting to report, but I've had some (slightly unpredictable) luck killing his first form in about 5 seconds. Turns out that a well placed nature form thorn spike will rip his face up but good. Because the spikes basically ignore wraparound armour, I've also been looking at using them to deal with his shellfish form as well, but I can't find an effective way to do it.
Don't get me started on the second form experiment - that boy just won't sit still, although with a bit of luck I have tagged him with a ceiling mounted spike.
Anyway, has anyone come up with good ways to bring him down fast?