Did you... just punch behemoth for 1513 dmg?
Yeah. It's the left leg critical exploit - see, left leg's critical table seems to be broken and, on the proc, may produce completely unrealistic results. By the game's rules, dealing more than 700 dmg in a hit to a behemoth shouldn't even be possible, but left leg crit surpasses that easily, as you see.
Her base damage is around 20, btw:
And here's the build (which is wrong, btw - should've aimed for 6 luck and better criticals for even more lulz):
2 missing perks are comprehension (turned out to be an overkill) and Divine Favor (obviously).
Though, I don't really need that exploit to punch behemoths to the death - my melee duo just stuns/knocks down/makes unconscious (lol) them to the infinity so, after one initial burst or so, they just lay on the ground while you pummel that hp bloat down. Left leg crit is just for convenience.