Clear the Swamp
Ivasaar chose to guard Queen Leena, who had some injuries, and treat her rather than engage in the fight against the wyrms. The others also didn't urge the man to help, as they understood the concern and longing he had.
In the meantime, despite being told that the wyrm's weak point was on its head, still, it wasn't so easy to hit its head with a direct hit. After all, the wyrms could and would nimbly dodge their approach.
And because the magus level elves were aiming for their head, the wyrms seemed to have started to know that their weak point had been revealed, and they seemed to be increasing their defensive system, especially to protect their heads.
"Dammit! How could this snake-like thing be so clever?!"
Every time Tristan swung his greatsword at the wyrm's neck, the wyrm would immediately abandon any form of attack and plunge back into the murky swamp water.
And then, they gave a surprise attack from below.
CLANK!