Iksa does not get out of the way (rolled 28 Ref save), taking 19-5=14 points of damage.
Round 666
Iksa stays on her feet (33 Fort save), taking 1 point of damage from the wind. The crab takes 1 point of damage, as well.
Iksa cannot penetrate the crab's shell with any of her attacks (best roll 32).
F3 screams, "Halt!", but Iksa ignores him (25 CL check; 27 Will save).
The crab snaps Iksa with all four claws, one in the spleen, for 84-20=64 points of damage.
Round 667
Iksa stays on her feet (21 Fort save), taking 3 points of damage from the wind. The crab takes 1 point of damage. The crab has 177 HP remaining. Iksa has 79 HP remaining.