I tried this 30-40 times yesterday and not even close to a win, though I almost had it once.
I understand the rotation of Terrorizing Roar>>Unleash Fury and you must get to the knockdown pad before he casts Unleash Fury which is his god-mode buff.
My problem has been that the cast bars are not showing when he casts sometimes, maybe lag?, anyway, all of a sudden he just one-shots my Sin with no casting of anything as far as I can tell or I miss the Unleash Fury and get snared by Hunter Claws and, of course, die.
I am doing this in hard mode with mostly gemmed Bossanian Prowler armor and some epic items. Is it easier in normal mode or was the hard part beating the Ape boss to the Iron Statues of the Moon structure?