The power of Menadion Set would help the Yggdrasill to repel the intruders and crack the secret of the tower.
Without Lith, those under the effect of the When All Are One array would lose the mass of a Divine Beast, making the gap in strength with the Golems abyssal. Without him, the invaders would have no reason to fight and the conflict would end.
Lith was still shapeshifting back into a Tiamat when the axes of the four Golems surrounding him came down, aiming for his neck. His body was still covered in the burns caused by the blue flames when a large pillar of Primordial Flames engulfed them all.
The white fire sent the Golem on Lith's left slamming against the one on his back and created an opening for Valtak to pull the Tiamat to safety.
In the euphoria from being finally ridden of pain and the excitement from their imminent victory, the Yggdrasill had forgotten about the dying Wyrm and the Champion of Fire.