Rogun ignores the crabs attacking him, but makes sure they pay attention to him. He turns his back to aid the sorceress, taking a claw scratch to the back of his ankle. He smashes the shell of Talashia's crab, leaving nothing but a twitching husk in the sand. Elandra tries to strike her crab, but misses.
Srasut switches targets to Elandra's crab, since Talashia's was downed, and his axe cracks straight through its shell. The ghostly axes also kill their targets, leaving the desert eerily silent for a moment. He pauses before using his dragon breath, since there is nothing alive to attack. Talashia's joyful expression is dashed to smithereens when she realizes she doesn't get to attack anything. Her joy quickly returns, however.
Two more crabs emerge from the sands, bigger than the previous assailants. One leaps towards Rogun, but Talashia is still ready with her spell. The poor creatures staggers backwards, still near enough Rogun for him to attack, and when the dust dies down, he can see that it has been severely wounded. The crab switches targets then, leaping suddenly in between Rogun and Talashia, latching onto her torso with its claws. She can see it start to extend pincers from where its mouth must be.
The other crab comes up behind Srasut, with malice in its eye stalks. The dragon man is quick, though, and the crab leaps through the air with nothing to hit but more sand. It turns around and clacks its claws, threatening Srasut.
Rogun takes 4 damage from the crab's opportunity attack. He reduces the crab on Talashia to 0 HP.
Srasut reduces the remaining three crabs to 0 HP.
Talashia will ready her action to use against the crab that attacks Rogun as above. She takes 11 damage from the crab. It is now adjacent to both Talashia and Rogun, though you are not flanking it. The second crab is adjacent to Srasut, with Elandra standing nearby but not adjacent.